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Avocado Consumption, Abdominal Adiposity, and Oral Glucose Tolerance Among Persons with Overweight and Obesity

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Background Although intake of Hass avocado has been cross-sectionally linked to lower abdominal obesity, knowledge of the effects of avocado consumption on abdominal adiposity and glycemic outcomes remains limited. Objective The effects of avocado consumption on abdominal adiposity, insulin resistance, oral-glucose-tolerance test (OGTT), and estimated β-cell function were evaluated. Methods A total of 105 adults aged 25–45 y (61% female) with BMI ≥25 kg/m2 were randomly assigned to an intervention (N = 53) that received a daily meal with 1 fresh Hass avocado or a control (N = 52) that received an isocaloric meal with similar ingredients without avocado for 12 wk. DXA was used to assess the primary outcomes of abdominal adiposity [visceral adipose tissue (VAT), subcutaneous abdominal adipose tissue (SAAT), and the ratio of VAT to SAAT (VS Ratio)]. Fasted glucose and insulin were used to assess the primary outcomes of insulin resistance (HOMA-IR), and insulin sensitivity (Matsuda index) and β-cell function (Insulinogenic index) were estimated using an OGTT. Changes between groups were compared using an ANCOVA. Secondary analyses were conducted based on sex. Results The control group exhibited a greater reduction in SAAT [–54.5 ± 155.8 g (control) compared with 17.4 ± 155.1 g (treatment), P = 0.017] and increase in VS Ratio [0.007 ± 0.047 (control) compared with –0.011 ± 0.044 (treatment), P = 0.024]. Among females, the treatment group exhibited a greater reduction in VAT [1.6 ± 89.8 g (control) compared with –32.9 ± 81.6 g (treatment), P = 0.021] and VS Ratio [0.01 ± 0.05 (control) compared with –0.01 ± 0.03 (treatment), P = 0.001]. Among males, there was no significant difference between groups in changes in abdominal adiposity or glycemic outcomes. Conclusions Daily consumption of 1 fresh Hass avocado changed abdominal adiposity distribution among females but did not facilitate improvements in peripheral insulin sensitivity or β-cell function among adults with overweight and obesity. This study was registered at clinicaltrials.gov as NCT02740439.
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The Journal of Nutrition
Obesity and Eating Disorders
Avocado Consumption, Abdominal Adiposity,
and Oral Glucose Tolerance Among Persons
with Overweight and Obesity
Naiman A Khan,1,2Caitlyn G Edwards,2Sharon V Thompson,2Bridget A Hannon,2Sarah K Burke,3
Anne DM Walk,4Richard WA Mackenzie,5Ginger E Reeser,1Barbara H Fiese,6,7Nicholas A Burd,1,2
and Hannah D Holscher1,2,8
1Department of Kinesiology and Community Health, University of Illinois, Urbana, IL, USA; 2Division of Nutritional Sciences, University
of Illinois, Urbana, IL, USA; 3Department of Physical Therapy, University of Florida, Gaineville, FL, USA; 4Department of Psychology,
Eastern Illinois University, Charleston, IL, USA; 5Department of Life Science, Whitelands College, University of Roehampton, London, UK;
6Department of Human Development and Family Studies, University of Illinois, Urbana, IL, USA; 7Family Resiliency Center, University of
Illinois, Urbana, IL, USA; and 8Department of Food Science and Human Nutrition, University of Illinois, Urbana, IL, USA
ABSTRACT
Background: Although intake of Hass avocado has been cross-sectionally linked to lower abdominal obesity,
knowledge of the effects of avocado consumption on abdominal adiposity and glycemic outcomes remains limited.
Objective: The effects of avocado consumption on abdominal adiposity, insulin resistance, oral-glucose-tolerance test
(OGTT), and estimated β-cell function were evaluated.
Methods: A total of 105 adults aged 25–45 y (61% female) with BMI 25 kg/m2were randomly assigned to an
intervention (N =53) that received a daily meal with 1 fresh Hass avocado or a control (N =52) that received an isocaloric
meal with similar ingredients without avocado for 12 wk. DXA was used to assess the primary outcomes of abdominal
adiposity [visceral adipose tissue (VAT), subcutaneous abdominal adipose tissue (SAAT), and the ratio of VAT to SAAT
(VS Ratio)]. Fasted glucose and insulin were used to assess the primary outcomes of insulin resistance (HOMA-IR),
and insulin sensitivity (Matsuda index) and β-cell function (Insulinogenic index) were estimated using an OGTT. Changes
between groups were compared using an ANCOVA. Secondary analyses were conducted based on sex.
Results: The control group exhibited a greater reduction in SAAT [–54.5 ±155.8 g (control) compared with 17.4 ±155.1
g (treatment), P=0.017] and increase in VS Ratio [0.007 ±0.047 (control) compared with –0.011 ±0.044 (treatment),
P=0.024]. Among females, the treatment group exhibited a greater reduction in VAT [1.6 ±89.8 g (control) compared
with –32.9 ±81.6 g (treatment), P=0.021] and VS Ratio [0.01 ±0.05 (control) compared with –0.01 ±0.03 (treatment),
P=0.001]. Among males, there was no signicant difference between groups in changes in abdominal adiposity or
glycemic outcomes.
Conclusions: Daily consumption of 1 fresh Hass avocado changed abdominal adiposity distribution among females
but did not facilitate improvements in peripheral insulin sensitivity or β-cell function among adults with overweight and
obesity. This study was registered at clinicaltrials.gov as NCT02740439. J Nutr 2021;151:2513–2521.
Keywords: ber, monounsaturated fatty acids, abdominal adiposity, insulin, obesity
Introduction
The epidemic of elevated overweight and obesity presents a
major public health challenge in the USA, currently affecting
70% of the adult population (1). Further, increased abdominal
obesity, a hallmark of fat or adiposity-related metabolic
dysfunction, impacts over 1 in 3 adults (2). Visceral adipose
tissue (VAT) is more closely associated with obesity-related
metabolic diseases than subcutaneous abdominal adipose tissue
(SAAT) (3–5). Increased VAT has been cross-sectionally and
prospectively implicated in impaired glucose tolerance and
insulin resistance, and onset of type 2 diabetes, relative to
other adipose depots (6,7). Dietary intervention offers a poten-
tially efcacious solution for abdominal obesity management;
however, the inuence of diet in reducing VAT is unclear.
Weight loss interventions can be effective in reducing VAT and
risk of type 2 diabetes (8,9), but unfortunately inducing and
maintaining weight loss is unsuccessful for most individuals
(10). Therefore, dietary approaches that promote reduction in
VAT and reduction in type 2 diabetes risk, without relying
on hypocaloric diets and weight loss, may hold translational
potential for individuals with overweight and obesity.
C
The Author(s) 2021. Published by Oxford University Press on behalf of the American Society for Nutrition. This is an Open Access article distributed under the terms
of the Creative Commons Attribution-NonCommercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution,
and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com
Manuscript received February 7, 2021. Initial review completed March 12, 2021. Revision accepted May 17, 2021.
First published online June 30, 2021; doi: https://doi.org/10.1093/jn/nxab187. 2513
Regular consumption of nutrient-dense whole foods can
serve as a nonpharmacological approach to modifying adipose
tissue distribution and alleviating the metabolic effects of
adiposity. The avocado (Persea americana) is a fruit that is
rich in dietary ber and MUFAs, 2 nutrients that are benecial
for metabolic health (11). One fresh Hass avocado (136 g)
contains 13 g MUFAs, 10 g ber, and carotenoids and
other bioactive components (12). Diets rich in MUFAs and
ber have received considerable attention for their potential to
reduce obesity and lower the risk of type 2 diabetes (13–15).
Avocado consumers have lower abdominal obesity compared
with nonconsumers (11,16). Further, in a longitudinal study
among over 55,000 individuals, habitual consumption of
avocados was associated with lower weight gain and reduced
risk of having overweight or obesity when assessed 11 y later
(17). In a recent 12-wk randomized controlled weight loss
study, it was demonstrated that avocados can be consumed
as part of a hypocaloric diet weight loss program as well
(18). Therefore, avocado consumption is not only a marker of
a higher quality diet but can also improve metabolic health
and weight status. However, the effects of daily avocado
consumption on adipose tissue distribution and related insulin
resistance, insulin sensitivity, and pancreatic β-cell function
are unclear. The present work involved an investigator-blinded
randomized controlled trial to examine the effects of consuming
a daily meal with an avocado, relative to an isocaloric meal
without the avocado, on abdominal adiposity, insulin resistance,
and oral glucose tolerance among young-to-middle-aged adults
with overweight or obesity. We hypothesized that participants
consuming a daily meal with an avocado would exhibit greater
declines in VAT, VS Ratio, insulin resistance, and improvement
in glycemic outcomes.
Methods
Participants and study design
A randomized controlled trial design [Persea americana for Total Health
(PATH) Study] was undertaken to assess the effects of daily avocado
consumption on abdominal adiposity and glycemic measures among
adults with overweight or obesity. Data collection procedures were
administered at baseline, prior to treatment allocation, and at follow-
up 12 wk later. All subjects provided written informed consent prior
to study participation. Procedures were administered in accordance
with the Declaration of Helsinki and were approved by the Ethics
Committee of the University of Illinois. The study was registered
as a clinical trial on clinicaltrials.gov (NCT02740439). Adults aged
between 25 and 45 y with a BMI 25 (in kg/m2) were recruited using
university e-mail listservs and yers posted in community buildings
and on buses frequented by the public. Data were collected in central
The research was funded by the Hass Avocado Board. SVT was supported by a
fellowship provided bythe College of Agricultural, Consumer, and Environmental
Sciences. BAH was supported by the Agriculture and Food Research Initiative
Competitive Grant no. 2015-68001-23248 from the USDA National Institute of
Food and Agriculture to Cooperative Extension.
Author disclosures: The authors report no conicts of interest.
HDH is a member of The Journal of Nutrition Editorial Board and played no role
in the evaluation of the manuscript.
Supplemental Tables 1 and 2 are available from the “Supplementary data” link
in the online posting of the article and from the same link in the online table of
contents at https://academic.oup.com/jn/.
Address correspondence to NAK (e-mail: nakhan2@illinois.edu).
Abbreviations used: FDR, false discovery rate; GLTEQ, Godin Leisure Time
Exercise Questionnaire; IGI, insulinogenic index; OGTT, oral-glucose-tolerance
test; PATH, Persea americana for Total Health; SAAT, subcut aneous abdominal
adipose tissue; VAT, visceral adipose tissue.
Illinois between 2016 and 2018. Participant exclusion criteria included
BMI <25, pregnancy or lactation, tobacco use, food allergies and
lactose intolerance, latex allergy, prior diagnosis of cognitive, metabolic,
and gastrointestinal disease, use of medications that alter normal
bowel function and metabolism, and prior malabsorptive or restrictive
bariatric surgery within previous 2 y. Given that previously published
research on avocado consumption effects on adipose tissue distribution
and glucose tolerance were lacking, an aprioripower calculation using
a moderate effect size (Cohen’s d =0.50), 2-sided αof 0.05, and 80%
power, estimated that a sample size of 64 participants/group would be
sufcient to address the primary study aims.
Study treatment and control meals
Randomization was completed by a member of the research team
(ADMW) who was not involved in data collection or administration
of the intervention. Participants randomly assigned to the treatment
group consumed 1 meal a day with 175 g (male) and 140 g
(female) fresh Hass avocado, whereas the control group consumed an
isocaloric meal matched for macronutrient composition without an
avocado. A complete description of the meals and ingredient list can
be found in Supplemental Table 1. Per serving (50 g), an avocado
provides 80 kcal. The majority of the calories in avocados (90%)
are derived from fats with the greatest proportion accounted for
by MUFAs (5 g/serving) and 1 g/serving for polyunsaturated and 1
g/serving for saturated fats. The carbohydrates are predominantly in
the form of dietary ber (4 out of 5 g/serving) whereas proteins are
only 1 g/serving. Avocados also provide 20 minerals and vitamins.
As outlined in Tab l e 1, owing to the macronutrient composition of
avocados, the treatment meals were higher in total ber and lower
in saturated fats and higher in MUFAs. Over 90% of the ingredients
were identical between the meals but were scaled to meet the desired
caloric and macronutrient proles. The energy content and proportion
of macronutrients of meals for females was 20% lower compared
with males due to estimated energy needs. The study meals were
provided on a 7-d menu cycle designed to be similar to a typical
American diet and meet the Acceptable Macronutrient Distribution
Ranges (AMDR) set by the Institute of Medicine (45% carbohydrates,
35% fat, and 15% protein). Examples of meals included modied
versions of Penne Pasta, Cranberry Salad, Spanish Rice, Asian Penne,
Turkey Wrap, Spring Bowl, and an Egg Scramble. Participants traveled
to the test site twice weekly to pick up meals. Insulated meal coolers, ice
packs, and information about food safety procedures were provided.
Compliance was assessed using daily logs that participants completed
to indicate meal consumption and, for participants in the intervention,
avocado consumption. Concealment of allocation was maintained using
sequentially numbered containers for meal dispensation. Additionally,
staff who prepared and provided participants with the meals were not
involved in the data collection procedures.
Dietary assessment
Background diet was monitored prior to and during the nal week
of the intervention. Participants were asked to record all beverages
and foods consumed for 7 d and were provided a food diary with
detailed instructions given by a trained member of the research staff
at the completion of their rst laboratory visit. In addition, the record
contained written instructions for recording food intake (including how
to describe food preparation methods, added fats, brand names, and
ingredients of mixed dishes and recipes) and visual aids to estimate
serving sizes. Trained staff entered food records into the Nutrition
Data Systems-Research Version 2015 [Nutrition Coordinating Center
(NCC), University of Minnesota, Minneapolis, MN, USA] software
under supervision of a registered dietitian (NAK).
Physical activity
Participants were asked to recall their average weekly physical activity
during their leisure time over the past month using the Godin
Leisure Time Exercise Questionnaire (GLTEQ) (19,20). The GLTEQ
contains 3 open-ended physical activity questions pertaining to the
average frequency of mild, moderate, and strenuous physical activities
2514 Khan et al.
TABLE 1 Nutrient comparison between meals with avocado (treatment) and without (control)
avocado provided to participants with overweight or obesity1
Control Treatment
Nutrient Males Females Males Females
Energy, kcal 662 530 660 528
Total ber, g 4.0 3.2 16.0 12.8
Soluble ber, g 1.0 0.8 6.0 4.8
Pectins, g 0.0 0.0 4.0 3.2
Insoluble ber, g 3.0 2.4 10.0 8.0
Protein, % 16 12.8 14 11.2
Total fat, % 39 40
SFAs, % 17 7
MUFAs, % 10 24
PUFAs, % 9 5
Carbohydrate, % 45 45
1Comparison of nutritional proles between daily meals consumed by participants with (intervention) and without a fresh Hass
avocado (treatment).
(with examples of each) during free time during a typical week. All
participants were asked to refrain from changes in their physical activity
levels throughout the intervention.
Anthropometrics and abdominal adiposity
assessment
Standing height and weight measurements were completed to calculate
BMI with participants wearing lightweight clothing and no shoes.
Height and weight were assessed using a stadiometer (model 240;
SECA) and a digital scale (WB-300 Plus; Tanita), respectively. Measures
were recorded in triplicate and the average value was used in the
analyses. Whole body, VAT, and SAAT components were estimated
using a Hologic Horizon W densitometer using the standard software
(APEX Software version 5.6.0.5; Hologic). These procedures have been
previously described in detail (21,22).
Oral-glucose-tolerance test.
At baseline and 12 wk, a standard oral-glucose-tolerance test (OGTT)
was administered following a 12-h overnight fast. Participants rested for
30 min prior to the insertion of a Teon catheter into an antecubital
vein for repeated blood sampling and remained patent by a 0.9% saline
drip. After baseline blood collection, participants ingested 75 g glucose
bolus (NOW foods) dissolved in 250 mL of water within 2 min (t=
0min)(21). Venous blood was collected at the following time points:
0, 15, 30, 45, 60, 90, and 120 min after glucose ingestion into EDTA
containing tubes (BD Biosciences). Blood glucose concentration was
determined using a biochemical analyzer (YSI 2900 Life Sciences) in
duplicate and subsequently centrifuged at 1000 ×gfor 10 min at
4C. Aliquots of plasma were frozen and stored at –20C until analyses.
Plasma insulin concentrations were determined using a commercially
available ELISA (ALPCO).
Plasma glucose and insulin concentrations were used to determine
the Matsuda index and HOMA-IR according to established formulas
(23,24). The Matsuda index was calculated by:
10,000
(( fastingglucose×f asting insulin)×(average glucoseval ues)×(averageinsul in values))
(1)
HOMA-IR was calculated by:
Fasting Gl ucose ×F asting Insul in
405 (2)
Further, the insulinogenic index (IGI) was utilized as a measure of β-
cell function and calculated as ratio of insulin concentration at 30 min
minus fasting insulin to the difference of glucose at the same time (25).
Statistical analyses
Data from participants who completed the 12-wk intervention
(control =53, treatment =52) were used to conduct per protocol
analyses (see Figure 1). We applied a cutoff of 80% compliance
for study meal consumption throughout the trial, for per protocol
analyses. Additionally, intent-to-treat analyses were conducted among
all participants who were randomly assigned and provided complete
data at baseline. Missing values at follow-up were carried forward from
baseline values for the intent-to-treat analyses.
Baseline differences in between groups were assessed by independent
samples t-test. Primary analyses, i.e., intervention effects on abdominal
adiposity (i.e., VAT, SAAT, VS Ratio), insulin resistance (i.e., HOMA-
IR), and OGTT (i.e., Matsuda index and IGI) measures were subjected
to a univariate ANCOVA whereby change (posttest–baseline) measures
were compared between groups, following adjustment of changes in
reported energy intake. Critical values were adjusted for false discovery
rate (FDR) to act as a check on ination of Type 1 error (26). In the
present analyses, the FDR was set to 0.05, the acceptable level of family-
wise error. Secondary analyses separated by sex were conducted since
there were signicant differences in adiposity variables between females
and males. Statistical signicance level was set at P<0.05 (2-tailed) and
data were analyzed using SPSS version 25 (IBM).
Results
Per protocol analyses
Participants and baseline variables.
Participant recruitment and inclusion/exclusion is illustrated
in Figure 1. One hundred and fty-six participants who were
randomly assigned provided complete data at baseline and
136 were retained in the study at follow-up. The overall
retention rate of the study was 87%. There were no discernable
differences in characteristics between participants who dropped
out of the study compared with those who remained in the study.
Specically, there were no signicant differences in age and
baseline adiposity and glycemic variables between participants
who dropped out compared with those who remained in the
study (all Ps>0.209).
Following exclusion of participants who either did not pro-
vide follow-up data for adiposity variables or those who did not
meet the compliance threshold of 80%, 105 participants were
included in the nal per protocol analyses for adiposity variables
of interest. Only 64 participants [34 (control), 30 (treatment)]
successfully completed both baseline and follow-up OGTT
measures for calculating HOMA-IR, Matsuda index, and IGI.
Participant demographic and anthropometric information is
summarized in Tabl e 2 . Persons with overweight comprised
41% of the sample whereas 59% had obesity. The majority
Avocado effects on adiposity and glucose tolerance 2515
FIGURE 1 Participant recruitment and inclusion/exclusion information.
of the participants were of Caucasian descent (80%) and
female (61%). Signicant differences in adiposity variables
were observed based on sex whereby females had higher
SAAT (2383.9 ±598.5 g compared with 1675.5 ±749.8
g, P<0.001) whereas males had a higher VS Ratio (0.43 ±
0.14 compared with 0.30 ±0.09, P<0.001). However, there
were no differences in VAT between males and females [711.7 ±
303.7 g (females) compared with 678.0 ±348.3 g (males),
P=0.601]. There were no signicant differences between
treatment and control group participants of the same sex.
Background diet and physical activity.
There were no statistically signicant differences in changes
in leisure time physical activity score between the treatment
and control groups [–3.6 ±29.9 (control) compared with
11.4 ±41.6 (treatment), P=0.59]. However, there was a
signicant difference between changes in energy consumption
between the control and treatment groups [–109.7 ±549.7
kcal (control) compared with 174.3 ±568.4 kcal (treatment),
P=0.011]. As the intervention aimed to maintain overall
caloric intake throughout the study and between groups,
subsequent statistical analyses adjusted for change in energy
consumption to account for background changes in energy
consumption between groups.
Intervention effects on central adiposity.
The baseline values for the adiposity measures are summarized
in Tabl e 3 for descriptive purposes. Baseline and follow-up
insulin resistance and sensitivity is described in Tabl e 4 .The
summary of statistical tests contrasting change in adiposity
2516 Khan et al.
TABLE 2 Baseline demographic information and anthropometric characteristics of adults with
overweight or obesity participating in the PATH randomized controlled trial1
All (N =105) Control (N =53) Treatment (N =52)
Age, y 34.5 ±5.9 34.2 ±6.0 34.9 ±5.8
Race, n(%)
White or Caucasian 83 (80) 42 (79) 41 (79)
Asian 11 (11) 5 (9) 6 (12)
Black or African American 5 (5) 3 (6) 2 (4)
American Indian or Alaska Native 1 (1) 1 (2) 0 (0)
Other and multiracial 4 (4) 2 (4) 2 (4)
Household income, n(%)
$41,000 28 (27) 14 (26) 14 (26)
$41,000–$70,000 39 (37) 21 (40) 18 (35)
$70,000 38 (36) 18 (34) 20 (39)
Height, cm 171.2 ±8.9 171.1 ±9.6 171.2 ±8.2
Weight, kg 95.7 ±19.4 96.9 ±20.5 94.5 ±18.4
BMI, kg/m232.6 ±6.1 33.0 ±6.2 32.1 ±6.0
Overweight (25–29.9) 43 (41) 21 (40) 22 (42)
Obesity Class 1 (30–34.9) 32 (31) 14 (26) 18 (35)
Obesity Class 2 (35–39.9) 17 (16) 8 (15) 9 (17)
Obesity Class 3 (40) 13 (12) 10 (19) 3 (6)
1Continuous data presented as mean ±SD where indicated. PATH, Persea americana for Total Health.
and glycemic outcomes is summarized in Tabl e 5 . There was
no signicant difference between groups in VAT. The control
group had a signicantly larger reduction in SAAT. There
was a signicant difference between groups in change in VS
Ratio. Examining the results based on sex revealed that, among
females, there was a signicant difference between groups in
changes in VAT, SAAT, and VS Ratio. On the other hand, among
males, there was no signicant difference between groups in
changes in VAT, SAAT, and VS Ratio. Following controlling for
FDR, the differences in changes in VS Ratio between groups
remained signicant. Similarly, the differences in changes in VS
Ratio and SAAT among females persisted following controlling
for FDR.
Intervention effects on insulin resistance and sensitivity.
The baseline values for the glucose- and insulin-based outcomes
are summarized in Tabl e 4 and comparison of changes
based on sex and group are summarized in Tabl e 5.There
was no difference between groups in changes in HOMA-
IR (P=0.100), Matsuda index (P=0.285), and the IGI
(P=0.67). Similarly, there were no changes among females or
males.
Intent-to-treat analyses
Intervention effects on central adiposity.
Intent-to-treat analyses for the adiposity variables were con-
ducted among all participants who were randomly assigned
and completed baseline testing in the control [N =79 (52
females; 27 males)] and treatment [N =77 (49 females; 28
males)] groups. There was no signicant difference between
groups in VAT (P=0.44).The control group had a signicantly
larger reduction in SAAT (P=0.012). However, there was a
difference between groups in VS Ratio (P=0.045). Examining
the results based on sex revealed that, among females, there
was no signicant difference between groups in changes in
VAT ( P=0.227). However, there were signicant differences
in SAAT (P=0.002), and VS Ratio (P=0.010). On the other
hand, among males, there was no signicant difference between
groups in changes in VAT (P=0.940), SAAT (P=0.545),
and VS Ratio (P=0.611). Following controlling for FDR, the
signicant differences in changes in VS Ratio and SAAT among
females persisted.
Intervention effects on insulin resistance and sensitivity.
There was a signicant difference between groups in changes
in HOMA-IR (P=0.036). However, there was no signicant
TABLE 3 Baseline and follow-up adiposity of adults with overweight or obesity participating in the PATH randomized controlled trial
based on sex and group1
Females Males
Control (N =34) Treatment (N =30) Control (N =19) Treatment (N =22)
Baseline Follow-up Baseline Follow-up Baseline Follow-up Baseline Follow-up
Weight, kg 94.6 ±18.6 94.4 ±18.3 92.4 ±16.6 92.0 ±16.5 101.0 ±23.5 99.9 ±23.7 97.3 ±20.7 97.9 ±20.9
Fat, % 44.3 ±6.2 44.0 ±6.2 42.9 ±4.3 42.5 ±4.6 32.3 ±8.6 31.6 ±8.2 31.6 ±7.6 31.9 ±7.7
VAT, g 743.9 ±334.0 745.5 ±324.2 675.2 ±266.1 642.3 ±258.0 672.4 ±409.3 618.4 ±351.4 682.8 ±295.8 664.7 ±272.5
SAAT, g 2476.6 ±595.0 2415.3 ±633.8 2279.0 ±594.7 2292.6 ±599.4 1701.2 ±792.4 1684.0 ±867.2 1653.4 ±729.2 1675.8 ±744.2
VS Ratio 0.30 ±0.10 0.31 ±0.11 0.29 ±0.08 0.28 ±0.08 0.42 ±0.16 0.40 ±0.17 0.44 ±0.12 0.41 ±0.11
1Data presented as mean ±SD. PATH, Persea americana for Total Health; SAAT, subcutaneous abdominal adipose tissue; VAT, visceral adipose tissue; VS Ratio, visceral to
subcutaneous abdominal adipose tissue.
Avocado effects on adiposity and glucose tolerance 2517
TABLE 4 Baseline and follow-up insulin resistance and sensitivity of adults with overweight or obesity participating in the PATH
randomized controlled trial based on sex and group1
Females Males
Control (N =21) Treatment (N =16) Control (N =13) Treatment (N =14)
Baseline Follow-up Baseline Follow-up Baseline Follow-up Baseline Follow-up
Glucose, mg/dL 83.5 ±12.5 82.7 ±11.5 77.5 ±13.8 82.3 ±11.0 80.4 ±10.2 84.3 ±14.0 80.7 ±11.3 87.7 ±8.7
Insulin, μIU/L 10.9 ±6.8 11.0 ±4.8 8.3 ±3.7 9.5 ±5.3 9.3 ±4.7 9.7 ±4.6 9.6 ±5.9 11.3 ±7.3
HOMA-IR 2.3 ±1.7 2.3 ±1.2 1.6 ±0.9 2.0 ±1.2 2.0 ±1.3 2.0 ±1.1 1.9 ±1.2 2.5 ±1.9
Matsuda index 5.4 ±3.2 5.0 ±2.7 6.7 ±4.4 5.6 ±3.8 5.2 ±2.5 4.6 ±2.4 5.5 ±3.2 4.5 ±2.5
Insulinogenic index 2.3 ±2.8 2.0 ±2.6 2.0 ±2.2 1.8 ±1.7 2.1 ±4.1 1.2 ±0.6 1.3 ±1.2 1.5 ±1.5
1Description of baseline insulin resistance and sensitivity values among participants with overweight and obesity allocated to a group consuming a daily fresh Hass avocado
(treatment) compared with a group consuming an isocaloric meal without avocado (control) for 12 wk. Data presented as mean ±SD. PATH, Persea americana for Total Health.
difference between groups in changes in Matsuda index
(P=0.286) and the IGI (P=0.779). There were no changes
among females (all Ps0.161) or males (all Ps0.16).
Following controlling for FDR, there were no signicant
differences in changes across glycemic outcomes.
Discussion
The present work determined the effects of daily avocado
consumption on abdominal adiposity, insulin resistance, and
oral glucose tolerance among adults with overweight and
obesity. There were signicant differences in VS Ratio between
groups, likely due to the greater change in SAAT among
control group participants. The greater reduction in SAAT
among control group participants was an unexpected result.
However, change in SAAT in the control group was not
associated with changes in overall energy consumption or
change in self-reported leisure time physical activity (data
not shown). Therefore, although we do not know the cause
of the SAAT change observed in the control group, this
change is not related to self-reported changes in overall energy
consumption and leisure time physical activity. Analyses based
on sex revealed that females in the treatment group exhibited a
greater reduction in VS Ratio whereas control group females
had a greater reduction in SAAT. However, there were no
improvements in HOMA-IR, insulin sensitivity, and β-cell
function (i.e., IGI).
Although avocado consumption is a marker of higher diet
quality and potentially protects against metabolic risk (11,16,
27,28), there has been limited experimental work on adiposity
and oral glucose tolerance outcomes. A recent hypocaloric
weight loss trial with the inclusion of avocado reported
reductions in adiposity and improvements in presumably
fasting glucose; however, there were no differences between the
treatment and control groups (18). Previous research observed
that avocado consumers had higher BMI, waist circumference,
and metabolic syndrome risk (16). In a longitudinal study
among over 55,000 older adults, it was observed that, among
avocado consumers who had healthy weight status at baseline,
there was a reduction in the odds of developing overweight or
obesity compared with those who did not eat avocado (17).
The present work revealed that consuming a daily meal with
an avocado improved fat distribution as indicated by a lower
VS Ratio among female participants. Relative to other adipose
tissue depots, VAT accumulation, surrounding internal organs
such as the liver, is associated with type 2 diabetes (6,29,30),
dyslipidemia (31), inammation, increased risk of thrombosis
(32,33), and nonalcoholic fatty liver disease (34). Therefore,
the decrease in VS Ratio among treatment group participants
suggests that avocado intake imparts a benecial abdominal
adiposity prole. However, given that these benets were not
observed among males, the robustness of the treatment effect
is limited and additional experimental research is needed to
further characterize the effects of daily avocado consumption
on fat distribution.
TABLE 5 Change in adiposity and glycemic outcomes among adults with overweight or obesity participating in the PATH
randomized controlled trial based on sex and group1
Females Males
Adiposity outcomes
Control
(N =34)
Treatment
(N =30) P
Control
(N =19)
Treatment
(N =22) P
VAT, g 1.6 ±89.8 –32.9 ±81.60.021 –39.7 ±99.2 –18.1 ±107.1 0.500
SAAT, g –61.2 ±152.7 13.7 ±133.10.0212–42.4 ±164.7 22.4 ±184.2 0.268
VS Ratio 0.117 ±0.047 –0.015 ±0.0300.0012–0.002 ±0.046 –0.007 ±0.057 0.812
Glycemic outcomes
Control
(N =21)
Treatment
(N =16) P
Control
(N =13)
Treatment
(N =14) P
HOMA-IR –0.02 ±0.99 0.34 ±0.89 0.377 0.10 ±1.0 0.43 ±0.80 0.332
Matsuda index –0.47 ±2.57 –1.12 ±2.26 0.412 –0.58 ±2.01 –0.95 ±1.82 0.615
Insulinogenic index –0.09 ±1.49 –0.26 ±1.28 0.611 –0.48 ±1.28 0.21 ±0.93 0.121
1Comparison of changes (), using univariate ANOVA following adjustment for changes in energy consumption, in adiposity and glycemic outcomes between participants with
overweight and obesity allocated to a group consuming a daily fresh Hass avocado (treatment) compared with a group consuming an isocaloric meal without avocado (control)
for 12 wk. Data presented as mean ±SD. Indicates signicant difference in changes (follow-up–post) between groups.
2Signicance retained following false discovery rate correction.
PATH , Persea americana for Total Health; SAAT, subcutaneous abdominal adipose tissue; VAT, visceral adipose tissue; VS Ratio, visceral to subcutaneous abdominal adipose
tissue.
2518 Khan et al.
The mechanisms by which avocados may contribute to
VAT changes are possibly derived from the higher ber and
MUFA content (16). A whole avocado contains 10 g of
total ber, contributing to 40% of the recommendations
among females or 30% for males. Greater dietary ber intake
is cross-sectionally associated with lower VAT (35,36)and
related to lower gains in VAT (37). Further, independent of
caloric restriction, supplemental ber intake reduces BMI and
waist circumference (38). Dietary ber, specically insoluble
ber (contributing to 70% of ber in an avocado), could
affect VAT by increasing fecal bulk and shortening transit
time (39), and lowering absorption of nutrients and energy
(40). Acutely, meals with higher dietary ber elicit a moderate
postprandial blood glucose response, stimulating a greater
sensation of satiety in healthy adults (41). It has also been
hypothesized that the elevated postprandial glucose and insulin
response can affect macronutrient partitioning in a manner
that favors adipose tissue accumulation, and that VAT may
be more susceptible to the inuence of high insulin responses
relative to SAAT (42,43). There is also evidence that the
lipid compositional properties of adipose tissue differentially
impact whole body and abdominal obesity (44). The degree
of obesity and abdominal distribution of body fat have
been negatively correlated with the MUFAs and n3PUFA
contents of adipose tissue. Given that SFAs were higher
and MUFAs were lower in perivisceral than in subcutaneous
fat, it is possible that consuming diets that substitute SFAs
with MUFAs has the potential to shift abdominal adipose
distribution. Indeed, dietary fatty acid intake is known to be an
important determinant of changes in adipose tissue composition
(45).
Regarding potential clinical or biological relevance of our
ndings, previous work indicates that inducing a 26% reduction
in VAT over the course of 12 mo, using a healthy eating and
physical activity/exercise program, corresponds to signicant
improvement in cardiorespiratory tness, plasma inammatory
markers, lipid proles, and OGTT (46). The change in VAT
tissue among females in the treatment group in the current
study was 5%; therefore, the change observed in our study
was modest. However, considering that the present study
was relatively short (3 mo) and did not include an exercise
component, the modest change in VAT is not surprising. It
is possible that maintaining the treatment regimen over the
course of a longer period could have provided the necessary
cumulative reduction in VAT to be clinically meaningful. A
previous large prospective study observed that annual increases
of 3%, 4%, and 3% of VAT, SAAT, and VS Ratio, respectively,
were related to an increased risk of diagnosis of diabetes among
adults with higher BMI (47). Interestingly, the proportional
changes in these measures in the present study were similar
in magnitude, albeit the SAAT effects were only observed in
the control group. Overall, the changes in abdominal adiposity
compartments observed in the present study were modest
but could have possible clinical signicance if the trajectories
for reduction in VAT and VS Ratio were accumulated over
a longer period of time. Future longer duration studies are
needed to characterize the clinical meaningfulness of these
ndings.
Interestingly, we observed selective benets of participating
in the intervention for females but not males. This is not entirely
surprising since sexual dimorphism in lifestyle interventions
targeting obesity have been observed previously (48,49).
Although the explanations for the sexual dimorphism observed
in obesity prevalence and differential responses to lifestyle
interventions are unclear, recent trends indicate that obesity
and extreme obesity prevalence have signicantly increased
among females, further increasing the need for interventions
targeting females. However, additional research that includes
equal samples of male participants is necessary to gain a com-
prehensive understanding of dietary intervention effects. The
majority of lifestyle interventions are predominantly comprised
of female participants (27% male compared with 73% female)
(49), resulting in limited knowledge on dietary implications
for adiposity among males. Although the proportions of males
(41%) in the present work was greater than most studies,
it is possible that we failed to observe signicant effects for
males due to inadequate sample size of males and/or lower
adiposity status of males compared with females at baseline.
Given the known differences in adiposity partitioning based
on sex, differential effects for adiposity may also have been
driven by the fact that the treatment could have contributed
to the participants’ nutrient recommendations differently. For
example, the avocado provided 51% of Adequate Intake for
ber for females and 42% for males. Future studies are needed
to determine the extent to which dosage impacts changes in
adiposity distribution between males and females following
avocado consumption.
The present work also examined the implications of daily
avocado consumption on insulin resistance, OGTT-derived
peripheral insulin sensitivity, and β-cell function. Adding
approximately half an avocado to a meal has been shown to
increase satiety 4–5 h later and reduce postprandial insulin
concentrations (50,51), suggesting that manipulation of meals
with avocado could promote both satiety and metabolic
benets. To our knowledge, the present study represents the rst
randomized controlled study to examine effects of consuming
a whole avocado on glucose and insulin over several months
among persons with overweight and obesity. We did not observe
signicant effects of avocado consumption for glucose and
insulin outcomes. Given that VAT and insulin sensitivity and
resistance are closely linked, this was a surprising nding.
However, it is possible that we did not observe benets for
glycemic outcomes due to the modest reductions in VAT among
females only. It is also possible that a longer intervention
duration is necessary to observe metabolic benets for insulin
sensitivity following avocado consumption. A limitation of the
study was that only a subsample of the participants were
able to successfully complete the OGTT procedure. This was
primarily due to the invasive nature of the procedure and
challenges in successful catheter placement among persons
with overweight and obesity (52,53). Therefore, the ndings
for OGTT should be interpreted with caution. Nevertheless,
these ndings are consistent with previous work that examined
glycemic responses following several weeks of consuming
nutrients found in avocados. Lerman-Garber and colleagues
observed that a high MUFA diet was associated with a greater
decrease in triglycerides; however, there were no benets for
glycemic measures following a test mixed-meal (28). Although
our ndings did not support our a priori hypothesis regarding
glycemic outcomes, this work suggests that daily consumption
of a meal including an avocado, a fruit that is rich in fatty acids,
does not detrimentally affect insulin resistance or oral glucose
tolerance among adults with overweight and obesity. Additional
experiments examining the effects of avocado consumption on
glucose and insulin responses is needed to further characterize
the effects of avocados on insulin resistance and sensitivity.
In conclusion, consumption of a daily meal with an
avocado altered abdominal fat distribution over a 12-wk period.
Avocado effects on adiposity and glucose tolerance 2519
However, there were no improvements in insulin sensitivity or
β-cell function. Future research is necessary to examine the
underlying causes of the differential adiposity-related ndings
based on sex. Given the increasing prevalence of excess
adiposity, there is a vital need to develop and test food-
based approaches to reducing adiposity as well as improving
metabolic health.
Acknowledgments
We would like to thank Christine Madden for her management
of the metabolic kitchen and production of the study meals. We
also acknowledge the contributions Corinne Cannavale, Mor-
gan Chojnacki, Melisa Bailey, Joe Beals, Jennifer Kaczmarek,
and Andrew Taylor for their assistance in conducting the testing
procedures.
The authors’ contributions were as follows—NAK, HDH,
NAB, and BHF: conceptualized and obtained funding for the
research; CGE, SVT, BAH, and SKB: conducted the research;
ADMW: conducted randomization procedures; NAK: analyzed
data; all authors: contributed to the interpretation of the results
and writing of the manuscript; NAK: had primary responsibility
for nal content; and all authors: read and approved the nal
manuscript.
Data Availability
Data described in the manuscript, code book, and analytic code
will be made available upon request pending application and
approval.
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Avocado effects on adiposity and glucose tolerance 2521
... Two studies analyzed the outcome of common bean or Phaseolus vulgaris consumption in the condition of T2DM and obesity [37,38]. Three studies evaluated the effect of avocado ingestion on abdominal adiposity and visceral adiposity in subjects with syndrome metabolic disease and obesity [39][40][41]. Finally, two studies measured the effects of nopal or Opuntia Ficus Indica intake on anthropometric and metabolic characteristics in obese type 2 diabetes patients [42,43]. ...
... Patient anthropometric outcomes and serum lipid parameters enlisted in included studies are shown in detail in Table 2. Two out of the fifteen studies were double-blinded, randomized, placebo-controlled trials with parallel groups [29,30]; two studies were randomized crossover trials [37,43]; two studies had a randomized, placebo-controlled, doubleblind design [35,38]; one study had a multicenter, randomized, controlled parallel-arm trial design [40]; one study was a single-center, randomized, 2-arm, controlled, parallel trial [41]; three studies were randomized controlled trials [31,34,39]; one study was a randomized, placebo-controlled, cross-over [36]; one study was a double-blind, placebo-controlled, clinical pilot trial [32]; one study was a prospective dietary intervention [42]; and finally, one study was a two-phase, randomized, double-blind, clinical trial [33]. Most of them included adults of both genders, while one study included exclusively women. ...
... As shown in Figure 2, the majority of randomized controlled trials (53.3%) had an unclear risk of bias for A and B criteria, random sequence generation, and allocation concealment due to insufficient information about the sequence generation process to allow the decision of "Low risk" or "High risk" [32][33][34][35][36]38,42,43]. Moreover, 46.6% of studies had a low risk in A and B criteria [29][30][31]37,[39][40][41]. In the mentioned studies, researchers define a random component in the sequence generation process using the "rand function" random number between 1 and 2 in Microsoft Office Excel [30,31]. ...
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Diet containing Mexican ancestral foods such as cocoa, nopal, avocado, and common bean have been individually reported to have beneficial effects on obesity and comorbidities. Methods: A systematic review and meta-analysis on the effect of Mexican ancestral foods on the anthropometric, lipid, and glycemic control variables in obese patients was performed following PRISMA guidelines. Data were analyzed using a random-effects model. Results: We selected 4664 articles from an initial search, of which only fifteen studies satisfied the inclusion criteria. Data for 1670 participants were analyzed: 843 in the intervention group and 827 in the control group. A significant reduction in body mass index (mean difference: −0.80 (−1.31 to −0.30)) (95% confidence interval), p = 0.002, heterogeneity I2 = 92% was showed after the ingestion of cocoa, nopal, avocado, or common bean. The mean difference for body weight was −0.57 (−1.93 to 0.79), waist of circumference: −0.16 (−2.54 to −2.21), total cholesterol: −5.04 (−11.5 to 1.08), triglycerides: −10.11 (−27.87 to 7.64), fasting glucose: −0.81 (−5.81 to 4.19), and insulin: −0.15 (−0.80 to 0.50). Mexican ancestral food supplementation seems to improve anthropometric, lipid, and glycemic control variables in obesity; however, more randomized controlled trials are needed to have further decisive evidence about dosage and method of supplementation and to increase the sample size.
... Unripe avocado is naturally enriched in MH, but we recognise that effects of MH enrichment cannot be isolated from possible effects produced by other bioactive components and nutrients in avocados. Several studies have investigated consumption of 0.5-1 whole avocado, daily, on health outcomes [16,34,36,37]. Daily consumption of a ripe avocado did not alter insulin sensitivity or glycaemic outcomes in response to an OGTT after 12 weeks of intervention in adults with overweight/obesity [34,37] or after 4 weeks in patients with type 2 diabetes [38]. ...
... Several studies have investigated consumption of 0.5-1 whole avocado, daily, on health outcomes [16,34,36,37]. Daily consumption of a ripe avocado did not alter insulin sensitivity or glycaemic outcomes in response to an OGTT after 12 weeks of intervention in adults with overweight/obesity [34,37] or after 4 weeks in patients with type 2 diabetes [38]. In contrast, a meta-analysis of 9 RCTs showed that 38-330 g/day of daily avocado consumption reduced total cholesterol and LDL-C in people with hypercholesterolemia or metabolic syndrome [32]. ...
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Background: Unripe avocados (Persea americana) are naturally enriched in mannoheptulose (MH), which is a candidate caloric restriction mimetic. Objectives: To evaluate the effects of a diet supplement made from unripe avocado on glucose tolerance, and cardiometabolic risk factors in free-living nondiabetic adults with obesity. Methods: In a double-blinded, randomised controlled trial, 60 adults (female n = 47, age 48 ± 13 years, BMI 34.0 ± 2.6 kg/m2) were stratified by sex and randomised to avocado extract (AvX, 10 g finely ground, freeze-dried unripe avocado) or placebo (10 g finely ground cornmeal plus 5% spinach powder) daily, for 12 weeks. The primary outcome was a change in glucose area under the curve (AUC) in response to a 75 g oral glucose tolerance test. A post-hoc analysis was subsequently performed in a subgroup with insulin AUC above the median of baseline values after removal of participants >2 SD from the mean. Results: There were no between-group differences in glucose AUC (p = 0.678), insulin AUC (p = 0.091), or cardiovascular outcomes. In the subgroup analysis, insulin AUC was lower in AxV versus placebo (p = 0.024). Conclusions: Daily consumption of unripe avocado extract enriched in MH did not alter glucose tolerance or insulin sensitivity in nondiabetic adults with obesity, but the data provided preliminary evidence for a benefit in insulin AUC in a subgroup of participants with elevated baseline postprandial insulin levels.
... Food-based management of blood glucose dysregulation, by potentially including avocado within patterns of eating, may be a cost-effective strategy for cardiometabolic disease risk reduction [33]. The findings of our study are consistent with the clinical evidence for avocado consumption and blood glucose regulation [34][35][36][37][38]. For example, replacing the carbohydrate components of a person's eating pattern with avocado during a breakfast meal, a study showed significantly reduced postprandial glucose levels [38]. ...
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Background Avocados are a rich source of nutrients including monounsaturated fats, dietary fibre and phytochemicals. Higher dietary quality is reported in studies of consumers with higher avocado intakes. The present study aimed to examine avocado consumption and cardiometabolic risk measures in a representative sample of Australian adults. Methods A cross-sectional analysis was performed using Australian Health Survey 2011-2013 (n = 2,736 observations). Day 1 24-hour recall data was used to examine reported avocado intake (whole avocados and avocado-containing products excluding avocado oil) and cardiometabolic risk measures (LDL, HDL, and total cholesterol, triglycerides, apolipoprotein B, HbA1c, plasma glucose, systolic and diastolic blood pressure). T-tests and chi square analyses were conducted between low (5.21 [95% CI: 4.63, 5.79] grams/day) and high (44.11 [95% CI: 35.89, 52.33] grams/day) consumers of avocado. Results 14.7% of Australians were ‘avocado consumers’ (n = 403 observations). Mean avocado intake was 24.63 (95% CI: 20.11, 29.15) grams per day, with a median intake of 10.40 (IQR: 4.49–26.00) grams per day for those considered ‘avocado consumers’. Consumers of avocados had a lower BMI and waist circumference (each, p ≤ 0.001), lower plasma glucose level (p = 0.03), and higher HDL cholesterol (p ≤ 0.001) when compared with non-consumers. A trend towards lower plasma glucose, HbA1c (each, p = 0.04) and higher dietary fibre intake (p = 0.05) was found between high and low consumers of avocado. Conclusions Our study suggests favourable outcomes for avocado intake and cardiometabolic characteristics of consumers. Future studies should explore glucose homeostasis using a clinical trial design to understand potential relationships between avocado intake and cardiometabolic risk factors.
... Visceral fat has unique metabolic properties and is linked to insulin resistance, which is a characteristic feature of metabolic syndrome (38). The distribution of body fat, specifically the amount of visceral fat, has been found to be strongly associated with glucose tolerance, hyperinsulinemia, hypertriglyceridemia, and arterial hypertension -all of which are components of metabolic syndrome (39). Studies have shown that individuals with larger amounts of visceral fat are at higher risk for developing metabolic syndrome. ...
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Background Metabolic syndrome (Mets) is considered a global epidemic of the 21st century, predisposing to cardiometabolic diseases. This study aims to describe and compare the body composition profiles between metabolic healthy (MH) and metabolic unhealthy (MU) phenotype in normal and obesity population in China, and to explore the predictive ability of body composition indices to distinguish MU by generating machine learning algorithms. Methods A cross-sectional study was conducted and the subjects who came to the hospital to receive a health examination were enrolled. Body composition was assessed using bioelectrical impedance analyser. A model generator with a gradient-boosting tree algorithm (LightGBM) combined with the SHapley Additive exPlanations method was adapted to train and interpret the model. Receiver-operating characteristic curves were used to analyze the predictive value. Results We found the significant difference in body composition parameters between the metabolic healthy normal weight (MHNW), metabolic healthy obesity (MHO), metabolic unhealthy normal weight (MUNW) and metabolic unhealthy obesity (MUO) individuals, especially among the MHNW, MUNW and MUO phenotype. MHNW phenotype had significantly lower whole fat mass (FM), trunk FM and trunk free fat mass (FFM), and had significantly lower visceral fat areas compared to MUNW and MUO phenotype, respectively. The bioimpedance phase angle, waist-hip ratio (WHR) and free fat mass index (FFMI) were found to be remarkably lower in MHNW than in MUNW and MUO groups, and lower in MHO than in MUO group. For predictive analysis, the LightGBM-based model identified 32 status-predicting features for MUNW with MHNW group as the reference, MUO with MHO as the reference and MUO with MHNW as the reference, achieved high discriminative power, with area under the curve (AUC) values of 0.842 [0.658, 1.000] for MUNW vs. MHNW, 0.746 [0.599, 0.893] for MUO vs. MHO and 0.968 [0.968, 1.000] for MUO and MHNW, respectively. A 2-variable model was developed for more practical clinical applications. WHR > 0.92 and FFMI > 18.5 kg/m² predict the increased risk of MU. Conclusion Body composition measurement and validation of this model could be a valuable approach for the early management and prevention of MU, whether in obese or normal population.
... Daily consumption of a meal with an avocado changed abdominal adiposity distribution among overweight/obese females (BMI ≥25 kg/m 2 ) over a 12-wk period compared to a control. The treatment group exhibited a greater reduction in visceral adipose tissue [1.6 ± 89.8 g (control) compared to -32.9 ± 81.6 g (treatment), P = 0.021] and visceral adipose/subcutaneous abdominal adipose ratio [0.01 ± 0.05 (control) compared to -0.01 ± 0.03 (treatment), P = 0.001], although no improvements in peripheral insulin sensitivity or β-cell function were observed [188]. Also, coffee and green tea consumption was able to exert a direct impact on lipolysis regulation. ...
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Consumer priorities in healthy diets and lifestyle boosted the demand for nutritious and functional foods as well as plant‐based ingredients. Avocado has become a food trend due to its nutritional and functional values, which in turn is increasing its consumption and production worldwide. Avocado edible portion has a high content of lipids, with the pulp and its oil being rich in monounsaturated fatty acids and essential omega − 3 and omega − 6 polyunsaturated fatty acids (PUFA). These fatty acids are mainly esterified in triacylglycerides, the major lipids in pulp, but also in minor components such as polar lipids (phospholipids and glycolipids). Polar lipids of avocado have been overlooked despite being recently highlighted with functional properties as well. The growth in the industry of avocado products is generating an increased amount of their byproducts, such as seed and peels (nonedible portions), still undervalued. The few studies on avocado byproducts pointed out that they also contain interesting lipids, with seeds particularly rich in polar lipids bearing PUFA, and thus can be reused as a source of add‐value phytochemical. Mass spectrometry‐based lipidomics approaches appear as an essential tool to unveil the complex lipid signature of avocado and its byproducts, contributing to the recognition of value‐added lipids and opening new avenues for their use in novel biotechnological applications. The present review provides an up‐to‐date overview of the lipid signature from avocado pulp, peel, seed, and its oils.
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This study aimed to investigate the satiety effects of isocalorically replacing carbohydrate energy in a meal with avocado-derived fats and fibers. In a randomized 3-arm, 6-h, crossover clinical trial, thirty-one overweight/obese adults consumed a low-fat control meal (CON, 76% carbohydrate, 14% fat as energy, 5 g fiber, ~640 kcal) or high-fat meals similar in total fat and energy, but increasing avocado-derived fat and fiber content from half (HA, 68 g; 51% carbohydrate, 40% fat as energy, 8.6 g fiber) or whole avocado (WA, 136 g; 50% carbohydrate, 43% fat as energy, 13.1 g fiber) on three separate occasions. Visual analog scales (VAS) assessed subjective satiety over 6 h. Hormones associated with satiety/appetite were measured in blood collected immediately after VAS. Stepwise multiple regression analysis was used to assess the relationship of VAS with hormones in WA and CON. Hunger suppression was enhanced after the WA compared to CON meal (p < 0.01). Subjects indicated feeling more satisfied after both HA and WA than CON (p < 0.05). Fullness was greater after CON and WA vs. HA (p < 0.005). PYY and GLP-1 were significantly elevated after WA vs. CON (p < 0.05), while insulin was significantly higher after CON vs. WA (p < 0.0001). Ghrelin was suppressed more by CON than WA (p < 0.05). Regression analysis indicated PYY was associated with subjective satiety after WA, whereas increased insulin predicted changes in subjective satiety after CON. Replacing carbohydrates in a high-carbohydrate meal with avocado-derived fat-fiber combination increased feelings of satiety mediated primarily by PYY vs. insulin. These findings may have important implications for addressing appetite management and metabolic concerns.
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Avocados contain nutrients and bioactive compounds that may help reduce the risk of becoming overweight/obese. We prospectively examined the effect of habitual avocado intake on changes in weight and body mass index (BMI). In the Adventist Health Study (AHS-2), a longitudinal cohort (~55,407; mean age ~56 years; U.S. and Canada), avocado intake (standard serving size 32 g/day) was assessed by a food frequency questionnaire (FFQ). Self-reported height and weight were collected at baseline. Self-reported follow-up weight was collected with follow-up questionnaires between four and 11 years after baseline. Using the generalized least squares (GLS) approach, we analyzed repeated measures of weight in relation to avocado intake. Marginal logistic regression analyses were used to calculate the odds of becoming overweight/obese, comparing low (>0 to <32 g/day) and high (≥32 g/day) avocado intake to non-consumers (reference). Avocado consumers who were normal weight at baseline, gained significantly less weight than non-consumers. The odds (OR (95% CI)) of becoming overweight/obese between baseline and follow-up was 0.93 (0.85, 1.01), and 0.85 (0.60, 1.19) for low and high avocado consumers, respectively. Habitual consumption of avocados may reduce adult weight gain, but odds of overweight/obesity are attenuated by differences in initial BMI values.
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Purpose: Despite the fact that extra virgin olive oil (EVOO) is widely used in obese individuals to treat cardiovascular diseases, the role of EVOO on weight/fat reduction remains unclear. We investigated the effects of energy-restricted diet containing EVOO on body composition and metabolic disruptions related to obesity. Methods: This is a randomized, double-blinded, placebo-controlled clinical trial in which 41 adult women with excess body fat (mean ± SD 27.0 ± 0.9 year old, 46.8 ± 0.6% of total body fat) received daily high-fat breakfasts containing 25 mL of soybean oil (control group, n = 20) or EVOO (EVOO group, n = 21) during nine consecutive weeks. Breakfasts were part of an energy-restricted normal-fat diets (-2090 kJ, ~32%E from fat). Anthropometric and dual-energy X-ray absorptiometry were assessed, and fasting blood was collected on the first and last day of the experiment. Results: Fat loss was ~80% higher on EVOO compared to the control group (mean ± SE: -2.4 ± 0.3 kg vs. -1.3 ± 0.4 kg, P = 0.037). EVOO also reduced diastolic blood pressure when compared to control (-5.1 ± 1.6 mmHg vs. +0.3 ± 1.2 mmHg, P = 0.011). Within-group differences (P < 0.050) were observed for HDL-c (-2.9 ± 1.2 mmol/L) and IL-10 (+0.9 ± 0.1 pg/mL) in control group, and for serum creatinine (+0.04 ± 0.01 µmol/L) and alkaline phosphatase (-3.3 ± 1.8 IU/L) in the EVOO group. There was also a trend for IL-1β EVOO reduction (-0.3 ± 0.1 pg/mL, P = 0.060). Conclusion: EVOO consumption reduced body fat and improved blood pressure. Our results indicate that EVOO should be included into energy-restricted programs for obesity treatment.
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We investigated BMI trajectory patterns before diabetes diagnosis and examined associated changes in visceral adiposity and glucose metabolism. 23,978 non-diabetic Japanese participants (2,789 women) aged 30–64 years were assessed with a mean follow-up of 7.6 years. Diabetes was diagnosed via fasting glucose, HbA1c, and self-report. Latent-class trajectory analyses were performed to identify BMI trajectories. Longitudinal changes in BMI, visceral adiposity, and glucose metabolism were estimated using mixed models. 1,892 individuals developed diabetes. Three distinct BMI trajectories were identified in adults developing and not developing diabetes, respectively. Among adults developing diabetes, 47.3% were classified as “medium BMI” (n = 895), and had increased mean BMI within the obesity category before diagnosis. The “low BMI” group (38.4%, n = 726) had an initial mean BMI of 21.9 kg/m2, and demonstrated small weight gain. The “high BMI” group (n = 271) were severely obese and showed greater increase in BMI until diagnosis. All groups which developed diabetes showed absolute and/or relative increase in visceral fat and impaired β-cell compensation for insulin resistance. All groups not developing diabetes showed measured variables were relatively stable during observation. These data suggest that visceral fat gain may induce β-cell failure in compensation for insulin resistance, resulting in diabetes regardless of obesity level.
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The common approach to the multiplicity problem calls for controlling the familywise error rate (FWER). This approach, though, has faults, and we point out a few. A different approach to problems of multiple significance testing is presented. It calls for controlling the expected proportion of falsely rejected hypotheses — the false discovery rate. This error rate is equivalent to the FWER when all hypotheses are true but is smaller otherwise. Therefore, in problems where the control of the false discovery rate rather than that of the FWER is desired, there is potential for a gain in power. A simple sequential Bonferronitype procedure is proved to control the false discovery rate for independent test statistics, and a simulation study shows that the gain in power is substantial. The use of the new procedure and the appropriateness of the criterion are illustrated with examples.
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Objective This study aimed to elucidate the relationship between glucose levels and insulin resistance and sensitivity obtained from oral glucose tolerance tests and neurophysiological indices of attention among adults with overweight and obesity. Methods Forty adults with overweight or obesity (BMI ≥ 25 kg/m²) underwent dual‐energy x‐ray absorptiometry to assess visceral adipose tissue. Repeated venous blood samples were collected during an oral glucose tolerance test to measure insulin resistance (homeostatic model assessment of insulin resistance) and indices of insulin sensitivity (Matsuda index and Stumvoll metabolic clearance rate). Attention was assessed using event‐related brain potentials recorded during a visual oddball task. Amplitude and latency of the P3 wave form in a central‐parietal region of interest were used to index attentional resource allocation and information processing speed. Results Following adjustment for visceral adipose tissue, reduced values of Matsuda index and Stumvoll metabolic clearance rate (indicating poor insulin sensitivity) were correlated with longer peak latency, whereas insulin area under the curve was positively related to peak latency, indicating slower information processing. Individuals with decreased insulin sensitivity (Matsuda index < 4.3) had significantly longer P3 latencies compared with individuals with normal insulin sensitivity. Conclusions Higher fasting glucose, but not homeostatic model assessment of insulin resistance, and reduced indices of glucose sensivity are associated with decrements in attention characterized by slower reaction time and slower information processing speed among adults with overweight and obesity.
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Background: There is strong epidemiologic evidence that dietary fiber intake is protective against overweight and obesity; however, results of intervention studies have been mixed. Soluble fiber beneficially affects metabolism, and fiber supplementation may be a feasible approach to improve body composition and glycemia in adults with overweight and obesity.Objective: We evaluated randomized controlled trials (RCTs) of isolated soluble fiber supplementation in overweight and obese adults on outcomes related to weight management [body mass index (BMI; in kg/m(2)), body weight, percentage of body fat, and waist circumference] and glucose and insulin metabolism (homeostasis model assessment of insulin resistance and fasting insulin) through a systematic review and meta-analysis.Design: We searched PubMed, Web of Science, Cumulative Index to Nursing and Allied Health Literature and Cochrane Library databases. Eligible studies were RCTs that compared isolated soluble fiber with placebo treatments without energy-restriction protocols. Random-effects models were used to estimate pooled effect sizes and 95% CIs. Meta-regressions were performed to assess outcomes in relation to the intervention duration, fiber dose, and fiber type. Publication bias was assessed via Begg's and Egger's tests and funnel plot inspection.Results: Findings from 12 RCTs (n = 609 participants) from 2 to 17 wk of duration are summarized in this review. Soluble fiber supplementation reduced BMI by 0.84 (95% CI: -1.35, -0.32; P = 0.001), body weight by 2.52 kg (95% CI: -4.25, -0.79 kg; P = 0.004), body fat by 0.41% (95% CI: -0.58%, -0.24%; P < 0.001), fasting glucose by 0.17 mmol/L (95% CI: -0.28, -0.06 mmol/L; P = 0.002), and fasting insulin by 15.88 pmol/L (95% CI: -29.05, -2.71 pmol/L; P = 0.02) compared with the effects of placebo treatments. No publication bias was identified. Considerable between-study heterogeneity was observed for most outcomes.Conclusions: Isolated soluble fiber supplementation improves anthropometric and metabolic outcomes in overweight and obese adults, thereby indicating that supplementation may improve fiber intake and health in these individuals. However, the interpretation of these findings warrants caution because of the considerable between-study heterogeneity. This trial was registered at clinicaltrials.gov as NCT03003897.
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Purpose: Trends in sedentary lifestyle may have influenced adult body composition and metabolic health among individuals at presumably healthy weights. This study examines the nationally representative prevalence of prediabetes and abdominal obesity among healthy-weight adults in 1988 through 2012. Methods: We analyzed the National Health and Nutrition Examination Survey (NHANES) III (1988-1994) and NHANES for the years 1999 to 2012, focusing on adults aged 20 years and older who have a body mass index (BMI) of 18.5 to 24.99 and do not have diabetes, either diagnosed or undiagnosed. We defined prediabetes using glycated hemoglobin (HbA1c) level ranges from 5.7% to 6.4%, as specified by the American Diabetes Association. Abdominal obesity was measured by waist circumference and waist-to-height ratio. Results: The prevalence of prediabetes among healthy-weight adults, aged 20 years and older and without diagnosed or undiagnosed diabetes, increased from 10.2% in 1988-1994 to 18.5% in 2012. Among individuals aged 45 years and older, the prevalence of prediabetes increased from 22.0% to 33.1%. The percentage of adults aged 20 years and older with an unhealthy waist circumference increased from 5.6% in 1988-1994 to 7.6% in 2012. The percentage of individuals with an unhealthy waist-to-height ratio increased from 27.2% in 1988-1994 to 33.7% in 2012. Adjusted models found that measures of abdominal obesity were not independent predictors of prediabetes among adults with a healthy BMI. Conclusions: Among individuals within a healthy BMI range, the prevalence of prediabetes and abdominal obesity has substantially increased. Abdominal obesity does not appear to be the primary cause of the increase.
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Importance Previous analyses of obesity trends among children and adolescents showed an increase between 1988-1994 and 1999-2000, but no change between 2003-2004 and 2011-2012, except for a significant decline among children aged 2 to 5 years. Objectives To provide estimates of obesity and extreme obesity prevalence for children and adolescents for 2011-2014 and investigate trends by age between 1988-1994 and 2013-2014. Design, Setting, and Participants Children and adolescents aged 2 to 19 years with measured weight and height in the 1988-1994 through 2013-2014 National Health and Nutrition Examination Surveys. Exposures Survey period. Main Outcomes and Measures Obesity was defined as a body mass index (BMI) at or above the sex-specific 95th percentile on the US Centers for Disease Control and Prevention (CDC) BMI-for-age growth charts. Extreme obesity was defined as a BMI at or above 120% of the sex-specific 95th percentile on the CDC BMI-for-age growth charts. Detailed estimates are presented for 2011-2014. The analyses of linear and quadratic trends in prevalence were conducted using 9 survey periods. Trend analyses between 2005-2006 and 2013-2014 also were conducted. Results Measurements from 40 780 children and adolescents (mean age, 11.0 years; 48.8% female) between 1988-1994 and 2013-2014 were analyzed. Among children and adolescents aged 2 to 19 years, the prevalence of obesity in 2011-2014 was 17.0% (95% CI, 15.5%-18.6%) and extreme obesity was 5.8% (95% CI, 4.9%-6.8%). Among children aged 2 to 5 years, obesity increased from 7.2% (95% CI, 5.8%-8.8%) in 1988-1994 to 13.9% (95% CI, 10.7%-17.7%) (P < .001) in 2003-2004 and then decreased to 9.4% (95% CI, 6.8%-12.6%) (P = .03) in 2013-2014. Among children aged 6 to 11 years, obesity increased from 11.3% (95% CI, 9.4%-13.4%) in 1988-1994 to 19.6% (95% CI, 17.1%-22.4%) (P < .001) in 2007-2008, and then did not change (2013-2014: 17.4% [95% CI, 13.8%-21.4%]; P = .44). Obesity increased among adolescents aged 12 to 19 years between 1988-1994 (10.5% [95% CI, 8.8%-12.5%]) and 2013-2014 (20.6% [95% CI, 16.2%-25.6%]; P < .001) as did extreme obesity among children aged 6 to 11 years (3.6% [95% CI, 2.5%-5.0%] in 1988-1994 to 4.3% [95% CI, 3.0%-6.1%] in 2013-2014; P = .02) and adolescents aged 12 to 19 years (2.6% [95% CI, 1.7%-3.9%] in 1988-1994 to 9.1% [95% CI, 7.0%-11.5%] in 2013-2014; P < .001). No significant trends were observed between 2005-2006 and 2013-2014 (P value range, .09-.87). Conclusions and Relevance In this nationally representative study of US children and adolescents aged 2 to 19 years, the prevalence of obesity in 2011-2014 was 17.0% and extreme obesity was 5.8%. Between 1988-1994 and 2013-2014, the prevalence of obesity increased until 2003-2004 and then decreased in children aged 2 to 5 years, increased until 2007-2008 and then leveled off in children aged 6 to 11 years, and increased among adolescents aged 12 to 19 years.