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This systematic review and meta-analysis of randomized controlled trials (RCTs) was performed to summarize the effect of caffeine intake on weight loss. We searched the following databases until November 2017: MEDLINE, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials. The relevant data were extracted and assessed for quality of the studies according to the Cochrane risk of bias tool. We estimated an intake-status regression coefficient (Beta) for each primary study and estimated the overall pooled Beta and SE using random effects meta-analysis on a double-log scale. Heterogeneity between studies was assessed by the Cochran Q statistic and I-squared tests (I²). Thirteen RCTs with 606 participants were included in the meta-analyses. The overall pooled Beta for the effect of caffeine intake was 0.29 (95%CI: 0.19, 0.40; Q = 124.5, I² = 91.2%) for weigh, 0.23 (95%CI: 0.09, 0.36; Q = 71.0, I² = 93.0%) for BMI, and 0.36 (95% CI: 0.24, 0.48; Q = 167.36, I² = 94.0%) for fat mass. For every doubling in caffeine intake, the mean reduction in weight, BMI, and fat mass increased 2 Beta-fold (20.29 = 1.22, 20.23 = 1.17, and 20.36 = 1.28), which corresponding to 22, 17, and 28 percent, respectively. Overall, the current meta-analysis demonstrated that caffeine intake might promote weight, BMI and body fat reduction.
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Critical Reviews in Food Science and Nutrition
ISSN: 1040-8398 (Print) 1549-7852 (Online) Journal homepage: http://www.tandfonline.com/loi/bfsn20
The effects of caffeine intake on weight loss: a
systematic review and dos-response meta-analysis
of randomized controlled trials
Reza Tabrizi, Parvane Saneei, Kamran B Lankarani, Maryam Akbari, Fariba
Kolahdooz, Ahmad Esmaillzadeh, Somayyeh Nadi-Ravandi, Majid Mazoochi
& Zatollah Asemi
To cite this article: Reza Tabrizi, Parvane Saneei, Kamran B Lankarani, Maryam Akbari, Fariba
Kolahdooz, Ahmad Esmaillzadeh, Somayyeh Nadi-Ravandi, Majid Mazoochi & Zatollah Asemi
(2018): The effects of caffeine intake on weight loss: a systematic review and dos-response meta-
analysis of randomized controlled trials, Critical Reviews in Food Science and Nutrition, DOI:
To link to this article: https://doi.org/10.1080/10408398.2018.1507996
Published online: 18 Oct 2018.
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The effects of caffeine intake on weight loss: a systematic review and
dos-response meta-analysis of randomized controlled trials
Reza Tabrizi
, Parvane Saneei
, Kamran B Lankarani
, Maryam Akbari
, Fariba Kolahdooz
, Ahmad
, Somayyeh Nadi-Ravandi
, Majid Mazoochi
, and Zatollah Asemi
Health Policy Research Center, Institute of Health, Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran;
Security Research Center, Department of Community Nutrition School of Nutrition and Food Science, Isfahan University of Medical Sciences,
Isfahan, Iran;
Health Policy Research Center, Shiraz University of Medical Sciences, Shiraz, Iran;
Indigenous and Global Health Research,
Department of Medicine, University of Alberta, Edmonton, Canada;
Department of Community Nutrition School of Nutritional Sciences and
Dietetics, Tehran University of Medical Sciences, Tehran, Iran;
Health Information Management Research Center, Kashan University of
Medical Sciences, Kashan, Iran;
Department of Cardiology School of Medicine, Kashan University of Medical Sciences, Kashan, Iran;
Research Center for Biochemistry and Nutrition in Metabolic Diseases, Kashan University of Medical Sciences, Kashan, Iran
This systematic review and meta-analysis of randomized controlled trials (RCTs) was performed to
summarize the effect of caffeine intake on weight loss. We searched the following databases until
November 2017: MEDLINE, EMBASE, Web of Science, and Cochrane Central Register of Controlled
Trials. The relevant data were extracted and assessed for quality of the studies according to the
Cochrane risk of bias tool. We estimated an intake-status regression coefficient (Beta) for each
primary study and estimated the overall pooled Beta and SE using random effects meta-analysis
on a double-log scale. Heterogeneity between studies was assessed by the Cochran Q statistic
and I-squared tests (I
). Thirteen RCTs with 606 participants were included in the meta-analyses.
The overall pooled Beta for the effect of caffeine intake was 0.29 (95%CI: 0.19, 0.40; Q ¼124.5,
¼91.2%) for weigh, 0.23 (95%CI: 0.09, 0.36; Q ¼71.0, I
¼93.0%) for BMI, and 0.36 (95% CI: 0.24,
0.48; Q ¼167.36, I
¼94.0%) for fat mass. For every doubling in caffeine intake, the mean reduction
in weight, BMI, and fat mass increased 2 Beta-fold (20.29 ¼1.22, 20.23 ¼1.17, and 20.36 ¼1.28),
which corresponding to 22, 17, and 28 percent, respectively. Overall, the current meta-analysis
demonstrated that caffeine intake might promote weight, BMI and body fat reduction.
Caffeine; weight loss;
An estimated 64% of American populations are overweight or
obese [body mass index (BMI) 25 kg/m
] (Flegal et al. 2002).
eases, including coronary heart diseases (CHD), hypertension,
type 2 diabetes mellitus (T2DM), pulmonary dysfunction, and
non-metabolic such as osteoarthritis, and certain types of can-
cer (Kromhout 1983;Lynchetal.2009). Common treatments
for managing obesity include lifestyle changes such as weight
loss, appropriate diet, and increased physical activity, as well as
the appropriate use of pharmacological agents to reduce the
specific risk factors (Villareal et al. 2011).
Modest weight loss, 510% of the initial body weight,
would result in beneficial health effects (Wing et al.
1992).Caffeine has been widely used as an practical approach
in obesity management (Astrup 2000). Caffeine increases both
noradrenaline and dopamine release, and therefore stimulates
the neuronal activity in several brain regions (Zheng and
Hasegawa 2016),whichinturncandecreaseweighandbody
fat. Caffeine may increase fat oxidation through inhibiting
phosphodiesterase and the suppression of negative effects of
adenosine on increased noradrenaline release (Dulloo,
Seydoux, and Girardier 1992). Despite reported anti-obesity
effects and weight maintenance of caffeine in some clinical
trials (Boozer et al. 2002; Coffey et al. 2004;Molnaretal.
2000; Westerterp-Plantenga, Lejeune, and Kovacs 2005), few
studies did not show any beneficiary effect of caffeine for
body weight and weight maintenance after weight loss (Hursel
and Westerterp-Plantenga 2009; Lee et al. 2005).Therefore, the
effect of caffeine consumption to improve weight loss diet and
reduce percentage of body fat remains controversial.
We are aware of no systematic review and meta-analysis
of RCTs about the effect of caffeine intake on weight loss.
This meta-analysis was performed to summarize the avail-
able evidence of RCTs to investigate the effect of caffeine
intake on weight loss.
Search strategy and study selection
This meta-analysis was undertaken according to PRISMA
(Preferred Reporting Items for Systematic Reviews and
CONTACT Zatollah Asemi asemi_r@yahoo.com Research Center for Biochemistry and Nutrition in Metabolic Diseases, Kashan University of Medical
Sciences, Kashan, Iran.
Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/bfsn.
ß2018 Taylor & Francis Group, LLC
Meta-Analyses) guideline. Two authors were independently
conducted the search, data selection, data extraction, and
evaluation of risk of bias. In the case of a disagreement, it is
resolved by consensus and/or discussion with a third author.
The following online databases were searched for relevant
RCTs studies published through November 2017: Cochrane
Library, EMBASE, MEDLINE, and Web of Science data-
bases. In addition, ongoing trials were searched from data-
bases including the International Standard Randomized
Controlled Trial Number Register and Meta-register for
RCTs. In addition, we did not publish the review protocol.
We conducted searches on gray literature using databases
including institute for scientific and technical information
(INIST) and the healthcare management information con-
sortium (HMIC), also to find other unpublished studies, we
contacted with experts and centers of related field. Trials
retrieved that examined the effect of caffeine intake on
weight, BMI and/or body fat by using the following MeSH
and text words [(caffeine[Mesh] OR coffee[Mesh] OR
caffeine [tiab] OR coffee [tiab]) OR caffeinated beverages
[tiab] AND (body weight[Mesh] OR body mass
index[Mesh] OR body fat[Mesh] OR body weight [tiab]
OR body mass index [tiab] OR body fat [tiab]) AND
(randomized clinical trial [pt] OR controlled clinical trials
[pt] OR randomized [tiab] OR placebo [tiab] OR randomly
[tiab] OR trial [tiab])].
The reference lists of all known related studies, including
original research papers and review articles, were reviewed as
an additional manual search. Trials applied that were pub-
lished in the English language without time restrictions for
Figure 1. Literature search and review flowchart for selection of studies.
Table 1. The effect of caffeine on weight, BMI and body fat reduction: overview of selected studies for dose-response meta-analysis.
Authors (y) Country
year Age (y) Gender
Sample size
intervention) RCT type
(name and daily dose)
(mg/day) Control
data Participants
Colker et al. (1999) USA 1999 Range: >21 y F/M 7/9 Parallel No 975 C aurantium, 528 mg
C, 900 mg St. Johns
240 Maltodextrin
6 Weight, body fat Overweight
Molnar et al. (2000) Hungary 2000 Mean: 16 ± 1 F/M
13/16 Parallel Yes <80 kg:300 mg C/30 mg
Or >80 kg: 600 mg
C/60 mg E
450 Placebo 20 Weight, BMI,
body fat
Boozer et al. (2002) USA 2002 Range: 18-80 F/M 38/39 Parallel Yes 192 mg C/90 mg E 192 Placebo 24 Weight, body fat Obese
Boozer et al. (2002) USA 2002 Range: 25-55 F/M 24/24 Parallel No 240 mg C/72 mg E 100 Placebo 8 Weight, body fat Overweight/
Coffey et al. (2004) USA 2004 Range: 18-65 F/M 50/52 Parallel No 360 mg C/60 mg E/
90 mg salicin
360 Placebo 12 Weight, BMI,
body fat
Greenway et al. (2004) USA 2004 Range: 18-65 F/M 20/20 Parallel Yes 210 mg C/72mg E 210 Placebo 12 Weight Healthy
Hackman et al. (2006) USA 2006 Range: 25-74 F 23/19 Parallel No 100 mg C/40 mg E 100 Placebo 36 Weight, body fat Overweight/
Thom (2007) Norway 2007 Mean: 24.2 ±3.2 F/M 15/15 crossover No 10 g of Coffee Slender 528 10 g of decaf-
12 Weight, body fat Overweight/
Hursel and
2009 Mean: 44 ± 2 F/M 20/20 Parallel No 150 mg C/270 mg
green tea
150 Placebo 13 Weight, BMI,
body fat
Bakuradze et al. (2011) Germany 2011 Range: 20-44 M 33/33 Consecuti-
No 750 ml freshly
brewed coffee
720 Water 8 Weight, BMI,
body fat
Liu et al. (2013) USA 2013 Range: 18-60 F/M 26/17 Parallel Yes 600 mg C/60 mg E 600 60 mg Leptin 24 Weight, body fat Obese
Bracale et al. (2014) Italy 2014 Mean:
36.3 ± 10.3
F 7/6 Parallel Yes 60 mg C/600 mg E 60 Placebo 4 Weight, BMI Obese
Davoodi et al. (2014) Iran 2014 Mean:
39.22 ± 5.81
F 30/30 Parallel Yes 5mg C/kg BW 425 Nothing 6 Weight, BMI,
body fat
F, Female; M, Male.
C, caffeine; E, ephedrine; OBLI, online basic lifestyle information; OBWM, online behavioral weight management; BEV, fortified diet cola beverage, soluble fiber dextrin and caffeine.
publication. Two authors (RT, MA) independently selected
studies in a two-steps process. In the first stage, authors
screened the titles and/or abstract for eligible trials. In the
second stage, the full-texts of related studies were retrieved to
assess the eligibility of selected studies using inclusion and
exclusion criteria. Studies did not contain proper data to be
included in the met-analysis, though presented the other
inclusion criteria were considered for a qualitative analyses to
help identify confounding parameters. Trials that met the
following criteria were selected for meta-analysis: (1) human
RCTs; (2) intervention group consumed caffeine or caffein-
ated coffee, whereas the control group received placebo; and
(3) the trials reported mean changes or mean difference
of weight and/or BMI and/or body fat loss with standard
deviation (SD) for the intervention and control groups or
reported enough data acquirable to assess Beta (B) and its
Standard Error (SE) for the assumed linear regression on the
Data extraction and quality assessment
Two independent authors (ZA and MA) extracted data from
each trial. The Cochrane Collaboration risk of bias tool was
used to assess the quality of all relevant RCTs based on the
following domains: random sequence generation, allocation
concealment, blinding of participants and outcome assess-
ment, incomplete outcome data, and selective outcome
reporting, and other sources of bias. The following data were
extracted: first authorsname, publication year, age, gender,
country, sample size, study design, energy restriction, the
dose of caffeine intake in intervention and control groups,
the duration of intervention, the mean change and standard
deviation on weight, BMI, and body fat in intervention and
control groups at the end of the intervention. We converted
the reported dosage of caffeine intake into milligram per day
Data analysis
We estimated a caffeine intake-status regression coefficient
(Beta) for each primary study on the baseline value when
the assumption of a linear correlation on the log
exists; caffeine intake compared with mean change weight,
BMI, and body fat. Algebraically derivation of an estimate
from primary study of the Beta and its SE, we compared
findings from studies with heterogeneously reported associa-
tions and the associated effects. The overall pooled Beta and
its SE were estimated by using random effects meta-analysis
following DerSimonian and Laird method (DerSimonian
and Laird 1986). In the meta-regression model, the equation
intercepts were calculated by using the meanX (the mean of
the caffeine intake on the ln scale) and the meanY (the
change of mean for weight, BMI, and fat mass status on the
ln scale) for every trial and weighted these by multiplying
with the weighting agent of the trial. Finally, we took the
mean of the weighted meanX and mean of the weighted
meanY as the coordination point at that the regression lines
were hung up. This point, together with Betas, presented the
intercept. All statistical transformation to provide Beta and
its SE were conducted using the Microsoft Excel version 7.0
(Microsoft, Inc). For each trial, we weighted these by multi-
plying with the weighting agent of the trial. Heterogeneity
between studies was assessed by Cochran Q test and I-
squared statistic (I
). I
higher than 50 percent with P-value
<0.05 represented significant heterogeneity. Potential source
of heterogeneity between studies such as duration of study
(12 weeks vs. <12 weeks), geographic area (US vs. non-
US), gender (female vs. male), and energy restriction (no vs.
yes) were examined by using subgroup analysis based on
stratified random effects meta-analysis. We used the median
of intervention duration, which was 12 weeks to do sub-
group analyses in order to have equal distribution of data
for comparison analyses. For linear dose response analyses,
we used the transformations method to derive coherent
single-study calculates from available summary statistics
(Souverein et al. 2012). The present study applied a basee
logarithmic transformation on the caffeine intake and mean
change of weight, BMI, and body fat before estimation of
trial-specific Betas, therefore the overall Beta provides the
difference in the loge-transformed and predicted mean
change of weight, BMI, and body fat for each 1 unit differ-
ence in the loge transformed value in caffeine intake.
Eggers test was used to detect the existence of potential
publication bias for the primary outcome measure. To meas-
ure the pooled estimates, nonparametric test (Duval and
Figure 2. The methodological quality of included studies based on review authorsjudgments about each risk of bias item presented as percentages across all
included studies.
Figure 3. AC. Random effects meta analysis of 13 randomized controlled trials that examined the association or effect of caffeine intake on change mean
(A) weight, (B) for BMI, (C) for body fat in intervention and control groups by using regression coefficients (Bets) for the liner association between loge-transformed
caffeine intake and loge transformed change mean in weight, BMI, and fat mass status (CI ¼95%).
Tweedie) was used. We used STATA version 12.0 (Stata
Corp., College Station, TX) and RevMan V.5.3 software
(Cochrane Collaboration, Copenhagen, Denmark) for data anal-
yses. P-Values <0.05 were considered as statistically significant.
Our initial search found 945 potential citations, after screen-
ing 13 trials with total of 606 participants were potentially
relevant and was included in the meta-analysis. Figure 1
shows the details of the study selection and Table 1 shows
the characteristics of the included studies that were pub-
lished between 1999 to 2014. Sample size varied between 13
to 102 participants. A consecutive design was performed in
one study, cross-over design in one study, and parallel group
design in the remaining 11 trials. To incorporating cross-
over trials, we were included only data from the first period.
Twelve trials have reported mean changes on weight
(Bakuradze et al. 2011; Boozer et al. 2002; Bracale et al.
2014; Coffey et al. 2004; Colker et al. 1999; Davoodi et al.
2014; Greenway et al. 2004; Hackman et al. 2006; Hursel
and Westerterp-Plantenga, 2009; Liu et al. 2013; Molnar
et al. 2000; Thom, 2007), six on BMI (Bakuradze et al. 2011;
Bracale et al. 2014; Coffey et al. 2004; Davoodi et al. 2014;
Hursel and Westerterp-Plantenga, 2009; Molnar et al. 2000),
and one on body fat loss (Greenway et al. 2004). The dur-
ation of intervention among trials varied between 4 and
36 weeks. The dosage of caffeine or caffeinated coffee in
intervention group was from 60 to 4000 mg/day (median:
360 mg/day). Seven trials were conducted in USA (Boozer
et al. 2002; Coffey et al. 2004; Colker et al. 1999; Greenway
et al. 2004; Hackman et al. 2006; Liu et al. 2013), and one in
each of the following countries, Iran (Davoodi et al. 2014),
Italy (Bracale et al. 2014), Germany (Bakuradze et al. 2011),
Netherlands (Hursel and Westerterp-Plantenga, 2009),
Hungary (Molnar et al. 2000), and Norway (Thom, 2007).
Figure 2 shows risk of bias of included trials.
The pooled analyses yielded a Beta coefficient of 0.29
(95%CI: 0.19, 0.40; Q ¼124.5, I
¼91.2%) for weight, 0.23
(95%CI: 0.09, 0.36; Q ¼71.0, I
¼93.0%) for BMI, and 0.36
(95%CI: 0.24, 0.48; Q ¼167.36, I
¼94.0%) for body fat
(Figures 3 and 4). The dose-response analyses showed that a
person who consumed 2 mg of caffeine per day compared to
1 mg of caffeine intake per day have 22% more reduction in
weight, 17% more reduction in BMI, and 28% more reduc-
tion in body fat.
The subgroup analysis for potential confounder variables
for heterogeneity including the dosage of caffeine intake, the
duration of the intervention, geographic area, gender, and
energy restriction are summarized in Table 2. The results of
subgroup analyses showed that the Betas were different in
some specific strata of suspected variables.
Eggers regression tests indicated no significant publica-
tion bias for the effect of caffeine intake on mean reduction
in weight (B ¼3.23, P¼0.22), and BMI (B ¼3.79,
P¼0.29). There was evidence of possible publication bias
in the effect of caffeine intake and fat mass (B ¼7.81,
P¼0.001). The results showed that the summary regression
coefficient (Beta) on body fat significantly decreased between
before (Beta 0.36; 95%CI, 0.24, 0.24) and after (Beta 0.22;
95%CI, 0.10, 0.34) censored trials were included into
the analysis.
This systematic review and meta-analysis is the first report
of the effect of caffeine intake on weight, BMI and body fat
and showed that caffeine intake might promote weight, BMI
and body fat reduction.
Obesity is associated with multiple metabolic and non-
metabolic disorders such as CHD, T2DM, and certain types of
cancer (Kromhout, 1983; Lynch et al. 2009). The current meta-
analysis of RCTs demonstrated that caffeine consumption
resulted in a significant decrease in weight, BMI and body fat.
In a meta-analysis by Phung et al.(Phung et al. 2010), it was
documented that the administration of green tea catechins
(GTCs) with caffeine was correlated with a significant decrease
in BMI, body weight, and waist circumference. Among healthy
people intake of green tea extract containing 270 mg of
Figure 4. AC. The change of mean weight, BMI, and fat mass status as a
function of dietary of caffeine intake (mg/d) calculated using random effects
meta-analyses of randomized controlled trails on )A) weight
[loge(y) ¼0.29 loge(x) 0.90], )B) BMI [loge(y) ¼0.23 loge(x) 1.93], )C)
body fat loge(y) ¼0.36 loge(x) 1.10].
epigallocatechin gallate and 150 mg of caffeine, were associated
with a significant increase in energy expenditure (by 4%)
compared with people who consumed caffeine alone. It was
also found that; there was a significant decrease in fat oxida-
tion (by 41%) for people who consumed green tea compared
with people who consumed caffeine (by 33%) (Dulloo et al.
1999). Few studies have reported the beneficial effects of caf-
feine on metabolic profiles. In a meta-analysis by Shi et al. (Shi
et al. 2016), caffeine intake significantly reduced insulin sensi-
tivity in healthy people. In another meta-analysis, the adminis-
tration of GTCs with or without caffeine led to a significant
drop in fasting glucose concentrations (Zheng et al. 2013).
Earlier, it was reported that the family of insulin-like growth
factors and their binding proteins involved in energy restriction
(Hamilton-Fairley et al. 1993), might interfere with reduction
in weight, BMI and body fat (Kiddy et al. 1989). Increased
insulin sensitivity would result in elevated IGF-binding pro-
tein-1 during short-term energy restriction (Moran et al. 2003).
In the current meta-analysis, we selected weight, BMI,
and body fat because they are known as the main diagnostic
variables in overweight and obese people, as well as being
the independent risk factors for CVD and diabetes (NHLBI
Obesity Education Initiative Expert Panel 1998). Despite the
statistical significance found between caffeine intake and
reduction in weight, BMI, and body fat in the current study,
the observed changes might not possibly be clinically rele-
vant. For instance, for anti-obesity agents available in the
market, subjects are considered to have failed their treat-
ment if they have not achieved a weight loss of 2 kg after
4 weeks of the therapy (NHLBI Obesity Education Initiative
Expert Panel 1998). It is noteworthy to mention that, in the
current meta-analysis, caffeine consumption provided an
average weight loss of <2 kg after 4 weeks of intervention
compared with the control group.
Caffeine intake may contribute to a decrease in anthropo-
metric measures through increased energy expenditure (Astrup
et al. 1990; Dulloo et al. 1989), and increased thermogenesis
(Astrup et al. 1990). Current evidence indicates the presence of
caffeine antagonize adenosine receptors (Graham 2001;Thong
and Graham 2002b) both in skeletal muscle (Graham 2001;
Han et al. 1998) and in the central nervous system, with the
latter results in an elevation in sympathetic activity (Thong
and Graham 2002a), which might results in weight loss.
The strengths of the current study include: (1) we made a
quantitative evaluation on how caffeine intake may influence
weight and BMI, based on the best available evidence from
RCTs; and (2) we combined all available dose in our dose-
response meta-analysis across a large range of exposure, and
the validity of the dose-response estimates have been increased.
There are several limitations in this meta-analysis, which
should be taken into consideration when assess the results.
Firstly, the number of studies, which were included in low-
grade and high-grade subgroup analyses, was too small to
gain solid conclusions; therefore more relevant studies are
Table 2. The effects of caffeine intake on weight, BMI and body fat reduction based on subgroup analysis.
of trials Subgroups
Pooled Beta
(random effect) 95% CI I-squared (%) Overall I-squared (%)
Weight Dosage of caffeine (mg/day) 3 <200 0.18 0.04, 0.32 86.2 91.2
5 200- 450 0.44 0.21, 0.67 95.9
3 450 <0.24 0.15, 0.33 0.0
Duration of study (week) 8 12 0.25 0.12, 0.39 91.7
413 0.37 0.17, 0.58 92.3
Geographic area 7 US 0.33 0.23, 0.44 82.8
5 Non US 0.24 0.04, 0.45 94.2
Gender 3 Female 0.11 0.09, 0.30 89.3
1 Male 0.18 0.02, 0.33
8 Both 0.38 0.26, 0.50 88.2
Energy restriction 6 No 0.33 0.24, 0.42 70.0
6 Yes 0.27 0.10, 0.44 93.7
BMI Dosage of caffeine (mg/day) 2 <200 0.10 0.06, 0.14 0.0 93.0
3 200- 450 0.33 0.07, 0.60 95.7
1 450 <0.21 0.06, 0.36
Duration of study (week) 4 12 0.20 0.01, 0.40 93.0
213 0.28 0.07, 0.62 95.8
Geographic area 1 US 0.46 0.36, 0.55
5 Non US 0.17 0.07, 0.28 85.1
Gender 2 Female 0.09 0.03, 0.15 0.0
1 Male 0.21 0.06, 0.36
3 Both 0.34 0.06, 0.61 96.8
Energy restriction 3 No 0.26 0.01, 0.50 95.7
3 Yes 0.20 0.03, 0.42 91.7
Fat mass Dosage of caffeine (mg/day) 4 <200 0.29 0.13, 0.46 94.0 94.0
4 200- 450 0.34 0.11, 0.56 95.6
3 450 <0.53 0.10, 0.96 94.3
Duration of study (week) 6 12 0.34 0.17, 0.52 94.6
513 0.39 0.20, 0.58 94.6
Geographic area 6 US 0.45 0.25, 0.65 94.1
5 Non US 0.27 0.11, 0.44 94.8
Gender 2 Female 0.30 0.17, 0.77 96.4
1 Male 0.12 0.01, 0.26
8 Both 0.41 0.27, 0.56 94.3
Energy restriction 7 No 0.38 0.23, 0.53 92.8
4 Yes 0.33 0.11, 0.55 95.7
needed to further explore this association. Secondly, sub-
stantial heterogeneity was observed across studies, which
was expected considering differences in types of caffeine
(e.g., only caffeine vs. caffeine plus other compositions), and
participantscharacteristics (e.g., gender, geographic region,
genetic background, and gene-environment interactions).
Thirdly, our search was limited to English language.
Overall, the current meta-analysis demonstrated that caf-
feine intake promoted weight, BMI and body fat reduction.
Additional prospective studies investigating the effect of caf-
feine supplementation on weight, BMI, and body fat loss
are necessary.
Disclosure statement
The current study was founded by a grant from the Vice-chancellor for
Research, Shiraz University of Medical Sciences, Shiraz, and Iran.
Kamran B Lankarani http://orcid.org/0000-0002-7524-9017
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... Several studies associated the anti-obesity effect of coffee to its bioactive compounds (CGAs, caffeine and melanoidins), which are also present in coffee silverskin, and different mechanisms have been proposed by which they regulate lipid metabolism, including modulation of cell signaling, inhibition of pancreatic lipase, regulation of hepatic lipid metabolismrelated enzymes, and reduction in hepatic fat accumulation in the rat model (70). In addition, a meta-analysis by Tabrizi et al. (71) suggested that the long-term consumption of caffeine sources might protect against type II diabetes through increased metabolic rate and thermogenesis, and stimulation of fat oxidation and free fatty acid release from peripheral tissues mediated by AMPK induction (Figure 3). ...
... Recently, a meta-analysis of randomized controlled trials concluded that caffeine has been widely used as a practical approach to obesity control by increasing the release of norepinephrine and dopamine and therefore stimulating neuronal activity in different brain regions, which in turn can decrease body weight and the fat content. Furthermore, this compound can increase fat oxidation by inhibiting phosphodiesterase and suppressing the inhibitory effects of adenosine on noradrenaline release, demonstrating that caffeine intake might promote weight, body mass index and body fat reduction (71). ...
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Coffee is one of the most consumed products in the world, and its by-products are mainly discarded as waste. In order to solve this problem and in the context of a sustainable industrial attitude, coffee by-products have been studied concerning their chemical and nutritional features for a potential application in foodstuffs or dietary supplements. Under this perspective, coffee silverskin, the main by-product of coffee roasting, stands out as a noteworthy source of nutrients and remarkable bioactive compounds, such as chlorogenic acids, caffeine, and melanoidins, among others. Such compounds have been demonstrating beneficial health properties in the context of metabolic disorders. This mini-review compiles and discusses the potential health benefits of coffee silverskin and its main bioactive components on metabolic syndrome, highlighting the main biochemical mechanisms involved, namely their effects upon intestinal sugar uptake, glucose and lipids metabolism, oxidative stress, and gut microbiota. Even though additional research on this coffee by-product is needed, silverskin can be highlighted as an interesting source of compounds that could be used in the prevention or co-treatment of metabolic syndrome. Simultaneously, the valorization of this by-product also responds to the sustainability and circular economy needs of the coffee chain.
... in few tea accessions, indicating that most tea plants were rich in caffeine 2 . Caffeine has antioxidant, anti-inflammatory, liver protection, diabetes prevention, cardiovascular protection, weight loss, anticancer and neurodegenerative diseases prevention and other health effects [3][4][5][6][7][8][9] . Nevertheless, the long-term or excessive intake of caffeine may cause insomnia, migraines, and changes in intraocular pressure 10 . ...
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Theacrine (1,3,7,9-tetramethyluric acid) is a natural product with remarkable pharmacological activities such as antidepressant, sedative and hypnotic activities, while caffeine (1,3,7-trimethylxanthine) has certain side effects to special populations. Hence, breeding tea plants with high theacrine and low caffeine will increase tea health benefits and promote consumption. In this study, we construct a F1 population by crossing “Zhongcha 302” (theacrine-free) and a tea germplasm “Ruyuan Kucha” (RY, theacrine-rich) to identify the causal gene for accumulating theacrine. The results showed that the content of theacrine was highly negative correlate with caffeine (R2 > 0.9). Bulked segregant RNA sequencing analysis, molecular markers and gene expression analysis indicating that the theacrine synthase (TcS) gene was the candidate gene. The TcS was located in the nucleus and cytoplasm, and the theacrine can be detected in stably genetic transformed tobacco by feeding the substrate 1,3,7-trimethyluric acid. Moreover, in vitro enzyme activity experiment revealed that the 241th amino acid residue was the key residue. Besides, we amplified the promoter region in several tea accessions with varied theacrine levels, and found a 234-bp deletion and a 271-bp insertion in RY. Both GUS histochemical analysis and dual-luciferase assay showed that TcS promoter activity in RY was relatively high. Lastly, we developed a molecular marker which is co-segregate with high-theacrine individuals in RY’s offspring. These results demonstrate that the novel TcS allele in RY results in the high-theacrine and low-caffeine traits and the developed functional marker will facilitate the breeding of characteristic tea plants.
... Most clinical studies that have examined the efficacy of caffeine on weight loss have been of short duration and many have used caffeine in combination with other ingredients. However, a recent meta-analysis of RCTs determined that caffeine consumption is associated with an average weight loss of <2 kg after 4 weeks [360]. Moreover, data from cross sectional and observational studies have suggested that increased caffeine intake is associated with less weight gain in the long-term [361], and may also be beneficial for the maintenance of weight loss [362]. ...
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Metabolic demands of skeletal muscle are substantial and are characterized normally as highly flexible and with a large dynamic range. Skeletal muscle composition (e.g., fiber type and mitochondrial content) and metabolism (e.g., capacity to switch between fatty acid and glucose substrates) are altered in obesity, with some changes proceeding and some following the development of the disease. Nonetheless, there are marked interindividual differences in skeletal muscle composition and metabolism in obesity, some of which have been associated with obesity risk and weight loss capacity. In this review, we discuss related molecular mechanisms and how current and novel treatment strategies may enhance weight loss capacity, particularly in diet-resistant obesity.
... Obesity is associated with many factors, such as energy imbalance between nutrition and physical activity, social environmental factors, and direct and indirect genetic effects (Arroyo-Johnson and Mincey 2016;. A series of studies have shown that caffeine could increase the body's metabolic rate and promote the decomposition of fat tissue and the oxidation of lipids, thus helping to reduce weight (Tabrizi et al. 2019) (Table 3). A meta-analysis of 19 studies showed that acute intake of caffeine increased the rate of fat oxidation with a dose-response effect during submaximal exercise after fasting. ...
Dietary intake of caffeine has significantly increased in recent years, and beneficial and harmful effects of caffeine have been extensively studied. This paper reviews antioxidant and anti-inflammatory activities of caffeine as well as its protective effects on cardiovascular diseases, obesity, diabetes mellitus, cancers, and neurodegenerative and liver diseases. In addition, we summarize the side effects of long-term or excessive caffeine consumption on sleep, migraine, intraocular pressure, pregnant women, children, and adolescents. The health benefits of caffeine depend on the amount of caffeine intake and the physical condition of consumers. Moderate intake of caffeine helps to prevent and modulate several diseases. However, the long-term or over-consumption of caffeine can lead to addiction, insomnia, migraine, and other side effects. In addition, children, adolescents, pregnant women, and people who are sensitive to caffeine should be recommended to restrict/reduce their intake to avoid potential adverse effects.
... Caffeine has been used as an approach in weight management because of its ability to stimulate both noradrenaline and dopamine secretions, which, in turn, may decrease BW and body fat (BF), as well as increase thermogenesis in brown adipose tissue via an unknown mechanism(s) [27]. A meta-analysis of 13 studies providing 60-4000 mg caffeine/day for 4-36 weeks showed that caffeine intake led to a reduction in BW, BF, and body mass index (BMI), and that this effect is dose-dependent [28]. However, all but three of the 13 included studies provided caffeine with other substances with potential weight loss properties. ...
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Dietary supplements for weight management include myriad ingredients with thermogenic, lipotropic, satiety, and other metabolic effects. Recently, the safety of this product category has been questioned. In this review, we summarize the safety evidence as well as relevant clinical findings on weight management and metabolic effects of six representative dietary supplement ingredients: caffeine, green tea extract (GTE), green coffee bean extract (GCBE), choline, glucomannan, and capsaicinoids and capsinoids. Of these, caffeine, GTE (specifically epigallocatechin gallate [EGCG]), and choline have recommended intake limits, which appear not to be exceeded when used according to manufacturers’ instructions. Serious adverse events from supplements with these ingredients are rare and typically involve unusually high intakes. As with any dietary component, the potential for gastrointestinal intolerance, as well as possible interactions with concomitant medications/supplements exist, and the health status of the consumer should be considered when consuming these components. Most of the ingredients reviewed also improved markers of metabolic health, such as glucose, lipids, and blood pressure, although the data are limited for some. In summary, weight management supplements containing caffeine, GTE, GCBE, choline, glucomannan, and capsaicinoids and capsinoids are generally safe when taken as directed and demonstrate metabolic health benefits for overweight and obese people.
... Adolescent athletes can be routinely approached with nutritional strategies to use CAF as ergogenic support; but we do not have evidence to guarantee its safety by assessing HRV after exercise. We cannot neglect CAF is one of the fat burners most used in clinical practice so as to help with weight loss in combination with physical exercise [46]. Consequently, we highlight those studies evaluating the effects of caffeine on cardiac recovery in overweight and obese individuals are still required to clarify the impacts of CAF on the cardiovascular health of this population. ...
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Aims Results regarding the effects of caffeine (CAF) intake on the autonomic control of heart rate recovery exercise remain inconclusive. Thus far, no study has used effect measures to pool the results of different experiments. We aim to assess the acute effect of CAF intake before exercise on the recovery of heart rate variability (HRV) after exercise through a systematic review and meta-analysis. Data synthesis Randomized controlled clinical trials were included; sample composed of physically active or trained adults; CAF should be offered/ingested before exercise, with dosage between 100-400 mg or between 2-6 mg/kg and administration/ingestion route analogous in the protocols; studies required to present results of HRV indices before and after exercise. Bias risk analysis and meta-analysis were performed. Twelve studies were included in the qualitative synthesis and five studies were encompassed in the quantitative synthesis (meta-analysis). For the Root-mean-square standard deviation (RMSSD) index we revealed p=0.67, Total 95% confidence interval (95% CI) ranged from -0.45 to 0.29, and 66.7% for heterogeneity between groups were reported. Concerning the High Frequency (HF) index, we observed p=0.22, Total 95% CI that ranged from -0.34 to 0.30, and 44% for heterogeneity between groups. Conclusions CAF intake did not affect heart rate variability recovery after exercise.
Background Energy drinks (EDs) are a type of beverage that mostly contains caffeine and other dietary supplements (if present) and does not contain any alcohol in the ingredients. The products in this category include Red Bull, Redline, Monster, Full Throttle, and others. They are claimed to help in boosting energy, stamina, sports performance, and concentration among individuals. This article focused on the review of the benefits and disadvantages of consumption of energy drinks to health and well-being. ED provides health benefits effects such as improved physical performance, mood and attitude, cognition, and weight loss. Some adverse negative health challenges have been linked to consumption of ED. Therefore, this review is a wholistic appraisal of benefits or detriments of consumption of energy drink to our health and suggestions to curtail the excesses of ED consumption. Main body Energy drink has been around since 1950, and it is marketed as energy booster and comes in different types, energy shots, fruit-based, non-fruit-based (regular), sugar-free, and plant-based. These products are marketed as a low-calorie “instant” energy drink that can be consumed in a single sip, or bottle to boost energy or to boost the nutritional value of conventional products. Many of them contain different ingredients such as caffeine, guarana, ginseng, yerba mate, acai berry, ginkgo biloba, methylxanthines, sugar, glucuronolactone, taurine, maltodextrin, B vitamins. Vitamin B2 (riboflavin), B3 (niacin), B6 (pyridoxine, pyridoxal, and pyridoxamine), Inositol B8 and B12, vitamin C and vitamin D; calcium, Iron, chromium, zinc, manganese, molybdenum; artificial sweeteners, aspartame, and sucralose. Health benefits such as improved physical performance, improved mood and attitude, improved concentration, and memory, good source of vitamin B and weight loss have been reported. Negative impact on health such as adverse cardiovascular effect, headaches, epileptic seizures, ischemic stroke, hallucinations, muscular twitching, restlessness, sleeplessness, anxiety, depression, gastrointestinal effect, renal effects, dental effects, obesity and type II diabetes, cancer, and caffeine toxicity has been reported. Conclusions Most of the health detriments caused because of consumption of energy drink is mostly due to the presence of excess quantity of caffeine and sugar. If the quantities of caffeine and sugar content in energy drink are kept at FDA- and WHO-recommended daily consumption amount, then it will not be present any problem to health. Consumption of energy drink that contains natural ingredients such as yerba mate, acai berry, ginkgo biloba, methylxanthines, amino acid, guarana, and ginseng with moderate FDA- and WHO-approved daily consumption of caffeine and sugar is not detrimental to health.
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To evaluate the influence of oral probiotic Bifidobacterium animalis subsp. lactis (BL-11) supplementation on salivary microbiota composition and the association with growth parameters, and behavioral symptoms in individuals with Prader-Willi syndrome (PWS). In this post hoc analysis, we included a subset of 36 PWS patients with available saliva samples from our original randomized, double-blinded, placebo-controlled trial (Chinese Clinical Trial Registry, ChiCTR1900022646, April 20, 2019). Among the 36 subjects, 17 subjects were allocated to the probiotic group for daily use of the BL-11 probiotic and 19 subjects were allocated to the placebo group. Groupwise and longitudinal differences in salivary microbiota abundances, biodiversity metrics, and height were analyzed. Linear correlations were found between identified differentially abundant salivary microbiota and clinical parameters. Salivary microbiome α-diversity was found to be higher in the probiotic-treated group at week 12 relative to placebo controls (P < 0.05). Leptotrichia, Paracoccus, and Faecalibacterium were found to be more abundant in the probiotic-treated group (P < 0.05). Salivary microbiota abundance and predicted functional profiling abundance correlations were found to be associated with anti-inflammation, anti-obesity, toxin degradation, and anti-oxidative injury effects (Q < 0.1). Several oral taxa also displayed correlations with social behavior severity scores in the probiotic-treated group (Q < 0.1). The findings suggest novel salivary microbiota compositional changes in response to the oral supplementation of BL-11 probiotic in individuals with PWS. The observed differentially abundant taxa between groups post-treatment were highly correlated with interventional effects on growth and social behaviors, although further investigation is warranted. Clinical Trial Registration The original clinical trial was registered under the Chinese Clinical Trial Registry with registration number ChiCTR1900022646 (April 20, 2019).
Background This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) is intended to provide clinicians an overview of the body weight effects of concomitant medications (i.e., pharmacotherapies not specifically for the treatment of obesity) and functional foods, as well as adverse side effects of common supplements sometimes used by patients with pre-obesity/obesity. Methods The scientific information for this CPS is based upon published scientific citations, clinical perspectives of OMA authors, and peer review by the Obesity Medicine Association leadership. Results This CPS outlines clinically relevant aspects of concomitant medications, functional foods, and many of the more common supplements as they relate to pre-obesity and obesity. Topics include a discussion of medications that may be associated with weight gain or loss, functional foods as they relate to obesity, and side effects of supplements (i.e., with a focus on supplements taken for weight loss). Special attention is given to the warnings and lack of regulation surrounding weight loss supplements. Conclusions This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) on concomitant medications, functional foods, and supplements is one of a series of OMA CPSs designed to assist clinicians in the care of patients with the disease of pre-obesity/obesity. Implementation of appropriate practices in these areas may improve the health of patients, especially those with adverse fat mass and adiposopathic metabolic consequences.
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Background According to previous meta-analyses, coffee consumption reduces the risk of type 2 diabetes mellitus. However, the underlying mechanism remains unknown. Whether caffeine, the key ingredient in coffee, has a beneficial effect on the glycemic homeostasis and the anti-diabetic effect is particularly controversial. The aim of this study was to summarize the effect of acute caffeine ingestion on insulin sensitivity in healthy men. MethodsA comprehensive literature search for papers published before April 2016 was conducted in EMBASE, PubMed, and Cochrane Library databases. Randomized controlled trials (RCTs) that investigated the effect of caffeine on insulin sensitivity in healthy humans without diabetes were included. A random effects meta-analysis was conducted using Review Manager 5.3. ResultsThe search yielded 7 RCTs in which caffeine intake was the single variant. Compared with placebo, caffeine intake significantly decreased the insulin sensitivity index, with a standardized mean difference of −2.06 (95% confidence interval −2.67 to −1.44, I2 = 49%, P for heterogeneity = 0.06). Conclusion Acute caffeine ingestion reduces insulin sensitivity in healthy subjects. Thus, in the short term, caffeine might shift glycemic homeostasis toward hyperglycemia. Long-term trials investigating the role of caffeine in the anti-diabetic effect of coffee are needed.
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Caffeine is a common substance in the diets of most athletes and it is now appearing in many new products, including energy drinks, sport gels, alcoholic beverages and diet aids. It can be a powerful ergogenic aid at levels that are considerably lower than the acceptable limit of the International Olympic Committee and could be beneficial in training and in competition. Caffeine does not improve maximal oxygen capacity directly, but could permit the athlete to train at a greater power output and/or to train longer. It has also ben shown to increase speed and/or power output in simulated race conditions. These effects have been found in activities that last as little as 60 seconds or as long as 2 hours. There is less information about the effects of caffeine on strength; however, recent work suggests no effect on maximal ability, but enhanced endurance or resistance to fatigue. There is no evidence that caffeine ingestion before exercise leads to dehydration, ion imbalance, or any other adverse effects. The ingestion of caffeine as coffee appears to be ineffective compared to doping with pure caffeine. Related compounds such as theophylline are also potent ergogenic aids. Caffeine may act synergistically with other drugs including ephedrine and anti-inflammatory agents. It appears that male and female athletes have similar caffeine pharmacokinetics, i.e., for a given dose of caffeine, the time course and absolute plasma concentrations of caffeine and its metabolites are the same. In addition, exercise or dehydration does not affect caffeine pharmacokinetics. The limited information available suggests that caffeine non-users and users respond similarly and that withdrawal from caffeine may not be important. The mechanism(s) by which caffeine elicits its ergogenic effects are unknown, but the popular theory that it enhances fat oxidation and spares muscle glycogen has very little support and is an incomplete explanation at best. Caffeine may work, in part, by creating a more favourable intracellular ionic environment in active muscle. This could facilitate force production by each motor unit.
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Context The prevalence of obesity and overweight increased in the United States between 1978 and 1991. More recent reports have suggested continued increases but are based on self-reported data.Objective To examine trends and prevalences of overweight (body mass index [BMI] ≥25) and obesity (BMI ≥30), using measured height and weight data.Design, Setting, and Participants Survey of 4115 adult men and women conducted in 1999 and 2000 as part of the National Health and Nutrition Examination Survey (NHANES), a nationally representative sample of the US population.Main Outcome Measure Age-adjusted prevalence of overweight, obesity, and extreme obesity compared with prior surveys, and sex-, age-, and race/ethnicity–specific estimates.Results The age-adjusted prevalence of obesity was 30.5% in 1999-2000 compared with 22.9% in NHANES III (1988-1994; P<.001). The prevalence of overweight also increased during this period from 55.9% to 64.5% (P<.001). Extreme obesity (BMI ≥40) also increased significantly in the population, from 2.9% to 4.7% (P = .002). Although not all changes were statistically significant, increases occurred for both men and women in all age groups and for non-Hispanic whites, non-Hispanic blacks, and Mexican Americans. Racial/ethnic groups did not differ significantly in the prevalence of obesity or overweight for men. Among women, obesity and overweight prevalences were highest among non-Hispanic black women. More than half of non-Hispanic black women aged 40 years or older were obese and more than 80% were overweight.Conclusions The increases in the prevalences of obesity and overweight previously observed continued in 1999-2000. The potential health benefits from reduction in overweight and obesity are of considerable public health importance.
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Low calorie diets are always difficult for obese subjects to follow and lead to metabolic and behavioral adaptation. Therefore, we evaluated the effect of caffeine treatment with calorie shifting diet (CSD) on weight loss. Female subjects (n=60; BMI≥25) completed 4-weeks control diet, 6-weeks CSD (3 repeated phases; each 2-weeks) and 4-weeks follow-up diet, with or without caffeine treatment (5 mg/Kg/day). The first 11 days of each phase included calorie restriction with four meals every day and 4 hours intervals. Significant weight and fat loss were observed after 4-weeks of CSD (5.7 ± 1.24 Kg and 4.84 ± 1.53 Kg) or CSD+Caffeine (7.57 ± 2.33 Kg and 5.24 ± 2.07 Kg) which was consistent for one month of the follow-up (CSD: 5.24 ± 1.83 Kg and 4.3 ± 1.62 Kg, CSD+Caffeine: 12.11 ± 2.31 Kg and 9.85 ± 1.6 Kg, p < 0.05 vs CSD group) and correlated to the restricted energy intake (p < 0.05). During three CSD phases, RMR tended to remain unchanged in both groups.While, CSD or CSD + Caffeine treatments, significantly decreased plasma glucose, total-cholesterol, and triacylglycerol (p < 0.05), even during follow-up period (p < 0.05). HDL-cholesterol was not changed by CSD. Feeling of hunger decreased and subject’s satisfaction increased after 4-weeks of CSD (p < 0.05) and remained low to the end of study, while satiety was not affected. Coffeine increased the effect of CSD on feeling of hunger and subject’s satisfaction after week 7 (p < 0.05 vs. CSD). These findings indicated that combination of caffeine treatment with CSD could be an effective alternative approach to weight and fat loss with small changes in RMR and improved tolerance of subjects to the new diet.
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Ephedrine/caffeine combination (EC) has been shown to induce a small-to-moderate weight loss in obese patients. Several mechanisms have been proposed, among which an increased thermogenic capacity of skeletal muscle consequent to the EC-induced up-regulation of uncoupling protein 3 (UCP3) gene expression. We did a parallel group double-blind, placebo-controlled, 4-week trial to investigate this hypothesis. Thirteen morbidly obese women (25–52 years of age, body-mass index 48.0±4.0 kg/m2, range 41.1–57.6) were randomly assigned to EC (200/20 mg, n = 6) or to placebo (n = 7) administered three times a day orally, before undergoing bariatric surgery. All individuals had an energy-deficit diet equal to about 70% of resting metabolic rate (RMR) diet (mean 5769±1105 kJ/day). The RMR analysed by intention to treat and the UCP3 (long and short isoform) mRNA levels in rectus abdominis were the primary outcomes. Body weight, plasma levels of adrenaline, noradrenaline, triglycerides, free fatty acids, glycerol, TSH, fT4, and fT3 were assessed, as well as fasting glucose, insulin and HOMA index, at baseline and at the end of treatments. Body weight loss was evident in both groups when compared to baseline values (overall −5.2±3.2%, p<0.0001) without significant differences between the treated groups. EC treatment increased the RMR (+9.2±6.8%, p = 0.020), differently from placebo which was linked to a reduction of RMR (−7.6±6.5%, p = 0.029). No significant differences were seen in other metabolic parameters. Notably, no changes of either UCP3 short or UCP3 long isoform mRNA levels were evident between EC and placebo group. Our study provides evidence that 4-week EC administration resulted in a pronounced thermogenic effect not related to muscle UCP3 gene expression and weight loss in morbidly obese females under controlled conditions. Trial Registration ClinicalTrials.gov NCT02048215
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The purpose of this study was to determine the effects of Citrus aurantium extract (an indirect beta-sympathicomimetic agent), caffeine, and St. John's Wort on body composition, metabolic variables, plasma lipid levels, and mood states in overweight healthy adults. In a double-masked, randomized, placebo-controlled study, 23 subjects with a body-mass index >25 kg/m2 were assigned to 1 of 3 groups. Group A received C aurantium extract 975 mg, caffeine 528 mg, and St. John's Wort 900 mg daily; group B received a maltodextrin placebo; and group C received nothing and served as the control group. For 6 weeks, subjects were instructed by a registered dictitian on how to follow an 1800-kcal/d American Heart Association Step One diet and performed a 3-day/week circuit training exercise program under the supervision of an exercise physiologist. During the exercise sessions, subjects achicved approximately 70% of age-predicted maximum heart rate. Compared with subjects in the placebo and control groups, subjects in the treatment group lost a significant amount of body weight (1.4 kg). They also lost a significant amount of body fat (an average change of 2.9%). In terms of actual fat loss, group A lost a significant amount (3.1 kg), whereas the control group demonstrated a tendency toward fat loss. No significant changes were noted in the results of the Profile of Mood States questionnaire for fatigue or vigor in any of the 3 groups. Group A expericnced a decrease, which did not reach statistical significance, of both plasma cholesterol and triglycerides. No significant changes in blood pressure, heart rate, electrocardiographic findings, serum chemistrics, or urinalysis findings were noted in any of the groups. Based on these results, it was concluded that the combination of C aurantium extract, caffeine, and St. John's Wort is safe and effective when combined with mild caloric restriction and exercise for promoting both body weight and fat loss in healthy overweight adults.
Objective: To evaluate the effects of combination caffeine/ephedrine and leptin A-200 on visceral fat mass and weight loss over 24 weeks. Design and methods: In this randomized, double-blind, parallel-arm trial, 90 obese subjects received one of the three treatments for 24 weeks: 200 mg caffeine/20 mg ephedrine t.i.d. (CE), leptin A-200 (recombinant methionyl human Fc-leptin, 20 mg q.d.) (L), or combination leptin A-200 and caffeine/ephedrine (LCE). Outcomes included change in weight, visceral fat mass by computed tomography, lean mass and fat mass by dual energy X-ray absorptiometry. Results: Groups treated with CE and LCE lost significant amounts of weight (-5.9 ± 1.2% and -6.5 ± 1.1%, P < 0.05) and whole body fat mass (-9.6 ± 2.4% and -12.4 ± 2.3%, P < 0.05) compared to leptin only group. Only treatment with LCE significantly reduced visceral fat mass (-11.0 ± 3.3%, P < 0.05). There were no differences in lean mass between treatment groups. Conclusions: Our study provides evidence that CE is a modestly effective weight loss agent and produces significant reductions in fat mass. Leptin A-200 was not effective in producing weight loss and did not have any significant additive or synergistic actions when combined with CE.
Background: The effect of green tea catechins (GTCs) with or without caffeine on glycemic control is controversial. Objective: We aimed to identify and quantify the effects of GTCs or GTC-caffeine mixtures on glucose metabolism in adults. Design: A comprehensive literature search was conducted to identify relevant trials of GTCs with or without caffeine on markers of glycemic control [fasting blood glucose (FBG), fasting blood insulin (FBI), glycated hemoglobin (Hb A1c), and homeostatic model assessment of insulin resistance (HOMA-IR)]. Weighted mean differences were calculated for net changes by using fixed-effects models. Prespecified subgroup analyses were performed to explore the influence of covariates on net changes in FBG and FBI concentrations. Results: Twenty-two eligible randomized controlled trials with 1584 subjects were identified. Pooled analyses showed that FBG (-1.48 mg/dL; 95% CI: -2.57, -0.40 mg/dL) decreased significantly with GTCs with or without caffeine, whereas FBI (0.04 μU/mL; 95% CI: -0.36, 0.45 μU/mL), Hb A1c (-0.04%; 95% CI: -0.15, 0.08%), and HOMA-IR (-0.05; 95% CI: -0.37, 0.26) did not. Subgroup analyses indicated that the glucose-lowering effect was apparent when the duration of follow-up was over a median of 12 wk. Overall, no significant heterogeneity was detected for FBG, FBI, Hb A1c, or HOMA-IR. Conclusions: The meta-analysis showed that the administration of GTCs with or without caffeine resulted in a significant reduction in FBG. The limited data available on GTCs did not support a positive effect on FBI, Hb A1c, or HOMA-IR. Thus, more large and well-designed trials are needed in the future. This trial was registered at http://www.crd.york.ac.uk/prospero as CRD42012002139.