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A pilot feasibility study exploring the effects of a moderate time-restricted feeding intervention on energy intake, adiposity and metabolic physiology in free-living human subjects


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This pilot study explored the feasibility of a moderate time-restricted feeding (TRF) intervention and its effects on adiposity and metabolism. For 10 weeks, a free-living TRF group delayed breakfast and advanced dinner by 1·5 h each. Changes in dietary intake, adiposity and fasting biochemistry (glucose, insulin, lipids) were compared with controls who maintained habitual feeding patterns. Thirteen participants (29 (sem 2) kg/m2) completed the study. The average daily feeding interval was successfully reduced in the TRF group (743 (sem 32) to 517 (sem 22) min/d; P < 0·001; n 7), although questionnaire responses indicated that social eating/drinking opportunities were negatively impacted. TRF participants reduced total daily energy intake (P = 0·019) despite ad libitum food access, with accompanying reductions in adiposity (P = 0·047). There were significant between-group differences in fasting glucose (P = 0·008), albeit driven primarily by an increase among controls. Larger studies can now be designed/powered, based on these novel preliminary qualitative and quantitative data, to ascertain and maximise the long-term sustainability of TRF.
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A pilot feasibility study exploring the effects of a moderate time-restricted
feeding intervention on energy intake, adiposity and metabolic physiology
in free-living human subjects
Rona Antoni*, Tracey M. Robertson, M. Denise Robertson and Jonathan D. Johnston
Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK
(Received 26 June 2018 Accepted 6 July 2018)
Journal of Nutritional Science (2018), vol. 7, e22, page 1 of 6 doi:10.1017/jns.2018.13
This pilot study explored the feasibility of a moderate time-restricted feeding (TRF) intervention and its effects on adiposity and metabolism. For 10 weeks,
a free-living TRF group delayed breakfast and advanced dinner by 1·5 h each. Changes in dietary intake, adiposity and fasting biochemistry (glucose, insulin,
lipids) were compared with controls who maintained habitual feeding patterns. Thirteen participants (29 (SEM 2) kg/m
) completed the study. The average
daily feeding interval was successfully reduced in the TRF group (743 (SEM 32) to 517 (SEM 22) min/d; P<0·001; n7), although questionnaire responses
indicated that social eating/drinking opportunities were negatively impacted. TRF participants reduced total daily energy intake (P=0·019) despite ad libitum
food access, with accompanying reductions in adiposity (P=0·047). There were signicant between-group differences in fasting glucose (P=0·008), albeit
driven primarily by an increase among controls. Larger studies can now be designed/powered, based on these novel preliminary qualitative and quantitative
data, to ascertain and maximise the long-term sustainability of TRF.
Key words: Chrononutrition: Circadian rhythms: Intermittent fasting: Metabolism: Food intake
Many aspects of mammalian metabolism exhibit daily rhythms,
driven by an integrated network of circadian clocks throughout
the body
. One consequence of metabolic rhythms is the
interaction between time of day and food intake (chrononutri-
. An emerging area of chrononutrition is time-restricted
feeding (TRF), in which the daily duration of food intake is
. TRF reduces animalsbody weight and improves
markers of metabolic health without altered energy consump-
.Benecial effects of TRF schedules on murine body
weight can occur within 8 weeks; lower fat mass and serum
cholesterol, together with improved glucose tolerance, occur
by the end of a 9-week protocol using a daily 15 h window
of food availability
In humans 24 h rhythms of glucose homeostasis and post-
prandial responses are well known
, but TRF data are
extremely limited. Most human TRF-related studies are limited
by short study duration, use of extreme temporal restriction
that is unrealistic for a long-term intervention, or change to
nocturnal energy intake as occurs during Ramadan
There is a clear need to develop human TRF research, using
protocols that reect realistic interventions for free-living indi-
viduals. The present 10-week study therefore aimed to assess
the feasibility of a TRF protocol in reducing the food intake
window, in addition to the effect and variability in changes
in several secondary outcomes (attrition rates, changes in diet-
ary intake, body weight, adiposity and fasting cardiometabolic
risk markers). Due to the lack of comparable TRF experiments
in human subjects, this work was conducted in the rst
instance as a pilot study using a controlled study design com-
paring control v. treatment groups.
Abbreviation: TRF, time-restricted feeding.
*Corresponding author: Dr Rona Antoni, email
© The Author(s) 2018. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creative-, which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is
properly cited.
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Sixteen healthy participants (BMI 2039 kg/m
) aged 2957
years were recruited. No a priori sample size was selected
with the intention that data obtained from this pilot study
would be used to inform power calculations for future work.
Participants were weight-stable (±2 kg) over the preceding 6
months and had no signicant medical history. Participants
were excluded if they had travelled across more than two
time zones within the month preceding the study or if they
had participated in rotating or night shift work for more
than 6 months. The study received a favourable ethical opinion
from the University of Surrey Ethics Committee. Written,
informed consent was obtained from all participants.
Study design
The study protocol is provided in Fig. 1(a). All participants
undertook a 2-week baseline period, during which they fol-
lowed habitual sleepwake and feedfast cycles. The timing
and composition of energy intake were recorded in diet diaries
over the nal 4 d. At the end of the baseline period, partici-
pants made an initial morning laboratory visit. Participants
abstained from alcohol and strenuous exercise for 24 h before
the visit, consumed their preceding evening meal before 20.00
hours and therefore arrived following at least a 12 h fasting per-
iod. Body weight and composition were measured by bioimpe-
dance (Tanita MC180A; Tanita Corp.). A fasting venous blood
sample was taken into K-EDTA tubes (TAG, cholesterol, insu-
lin analysis) and sodium oxalate tubes (glucose analysis).
After the initial laboratory visit, participants were assigned to
the control (n7) or TRF (n9) group, ensuring no statistical dif-
ferences in average age, BMI and body fat between groups.
Both groups undertook a 10-week intervention period at
home. The TRF group delayed rst energy intake of the day
and advanced last energy intake of the day, each by 1·5h,com-
pared with their dietary patterns calculated from the baseline
diaries. The symmetrical compression of energy intake in the
TRF group was chosen to minimise possible effects of morning
v. evening differences in metabolism and thus increase
likelihood that physiological changes were due to feeding dur-
ation per se, rather than time-of-day effects. Control participants
maintained the dietary patterns reported in their baseline diaries.
Both groups were asked to maintain habitual sleepwake pat-
terns. The timing and composition of energy intake were
recorded in diet diaries over four consecutive days on two occa-
sions during the intervention: mid-way through the intervention
period (week 5) and in the nal week (week 10). At the end of
the 10th intervention week, participants made a repeat labora-
tory visit and were asked to consume the same evening meal
as they did prior to the rst laboratory visit. Completing parti-
cipants were also given a questionnaire to assess their subjective
experience of following the dietary pattern (Table 1).
Dietary analysis
Participants recorded food intake in validated diet diaries
which included pictorial guides to aid portion size estimations
Table 1. Baseline characteristics for study completers in time-restricted
feeding (TRF) and control groups
(Mean values with their standard errors; numbers of participants)
TRF (n7) Control (n6)
TRF v. controlMean SEM Mean SEM
Age (years) 47 3 45 4 NS
Sex (n)NS
Male 1 0
Female 6 6
Weight (kg) 86·25·277·87·6NS
BMI (kg/m
Body fat (%)* NS
All 36·02·934·63·5NS
Males 21·9 N/A N/A N/A
Females 38·41·934·63·5NS
N/A, not applicable.
* Bioimpedance.
Fig. 1. Study design and effect of time-restricted feeding (TRF) on food intake.
(a) Participants had 2-week baseline on habitual meal times and were then
split into one of two groups for a 10-week intervention period; a control
group maintained habitual meal times, whereas a TRF group restricted their
daily feeding duration by 3 h. Diet, body weight, adiposity and fasting blood
markers were assessed in the final week of the baseline and intervention per-
iods. Dietary assessment was also made during week 5 of the intervention per-
iod. (b) Average daily energy intake in both groups at baseline and 10 weeks of
the interventions. (c) and (d) Distribution of daily energy intake in each group
during assessments at (c) baseline and (d) week 10 of the intervention period.
Data are presented as means, with standard errors represented by vertical
bars. –––, Control group (n5); ---, TRF group (n7). Pvalues represent the
group x time interactions.
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when exact weights could not be provided. Diet diary analysis
was performed with Diet Plan 7 (Foresteld Software), using
the McCance and Widdowsons composition of foods inte-
grated dataset. Generic foods in the nutritional analysis pro-
gram were used unless specic food brands were provided,
in which case nutritional composition information was manu-
ally inputted as a user added food. Recorded time of rst and
last energy-containing food was used to calculate the daily eat-
ing window. To assess for changes in daily energy intake dis-
tribution, each individual participants daily eating window was
divided into three time periods (thirds): early, mid, and late.
Analysis of fasting blood samples
Blood plasma aliquots were stored at 20°C. Insulin was ana-
lysed using ELISA (Millipore); glucose, TAG, total cholesterol
and HDL-cholesterol were analysed using commercial kits for
the ILAB650 (Instrumentation Laboratory). LDL-cholesterol
was calculated using the Friedewald equation
. Intra-assay
CV were <5 %.
An exit questionnaire was devised for the study to allow par-
ticipants to provide a subjective assessment of the intervention
and to suggest modications to the TRF protocol which could
be used by future studies to improve compliance. Questions
included: (1) How difcult did you nd the intervention?;
(2) Do you think you could maintain this protocol for longer
than 10 weeks?; (3) What were your main reasons for non-
compliance?; (4) Do you think the plan made you eat differ-
ently?; (5) Do you think you might carry on with the plan in
any form?.
Statistical analyses were performed on data from participants
who completed the study. Data were tested for normality using
the ShapiroWilk test. Differences between intervention groups
at baseline were assessed using independent ttests for continuous
variables or the χ
test for categorical variables, with any signi-
cant differences reported in the text. Paired ttests were used to
assess for within-group changes over the intervention period.
Other data were analysed using a two-way ANOVA, with the
period of daily eating window or laboratory visit as a repeated
measure. Where data were not normally distributed, non-
parametric tests were used to assess between-group differences
(MannWhitney U) and within-group changes (Wilcoxon
signed-rank test). Moreover, due to the small sample size, data
were also inspected for outliers; where outliers were observed
(adiposity) but exhibited normality using the ShapiroWilk test,
non-parametric tests were also used owing to their greater resili-
ence against outliers. Due to lower completion rates, intervention
week 5 dietary intake data are presented as Supplementary mater-
ial (Supplementary Fig. S1 and Table S2), but are not included in
the primary statistical analyses. We tested the hypothesis that the
TRF intervention would result in a signicant group × time inter-
action. Data are presented as mean values with their standard
errors unless otherwise stated.
Results and discussion
Recruitment, attrition and feasibility of time-restricted feeding
A total of sixteen healthy and overweight individuals were ini-
tially recruited into the study. Overall, attrition rates were low.
One control subject dropped out due to faintness during
blood collection at the rst clinical visit so did not commence
the study. Within the TRF group, seven of the nine partici-
pants successfully completed the 10-week intervention. One
TRF participant was lost to follow-up and so the reason for
drop out is unknown but may relate to the TRF intervention.
The second TRF participant was excluded as they had partici-
pated in another research project (resulting in changes to their
habitual diet), and therefore the reason for drop out was not
due to difculties with adhering to the TRF intervention.
Participants in the TRF group were asked to delay and
advance the timing of their rst and last energy intakes, respect-
ively, by 1·5 h, with no restrictions placed on meal frequency or
overall energy intake. This differs from recent studies in which
male participants ate three prescribed meals per d
Moreover, the symmetrical change in feeding duration differs
from asymmetrical reductions in feeding duration in which
physiological changes could result from time-of-day effects in
addition to any consequence of TRF. In our study, the total
eating window was reduced by an average of about 4·5h
(from 743 (SEM 32) and 517 (SEM 22) min/d) based on compar-
isons between 4 d dietary records kept at baseline and the nal
Fig. 1. (Continued)
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week of the intervention; participants achieved their target eating
window (3hreductionv. baseline) on average about 2·5/4 d in
week 10. By comparison, there was minimal change in the feed-
ing window of the control group (652 (SEM 50) to 677 (SEM 41)
min/d), resulting in a signicant group × time interaction
(P<0·001; two-way repeated-measures ANOVA).
Therefore, these data suggest that the TRF intervention was
achievable over a 10-week time-frame. However, many partici-
pants found it difcult to stick to the regimen every day, and
questionnaire data revealed an average difculty score of 7/10
(1: easy; 10: extremely difcult) among TRF participants.
Some common themes emerged from the questionnaires,
with most participants reporting TRF protocol deviations
occurring due to social eating/drinking events. Other reasons
reported by one participant included illness and a late running
work meeting. Of TRF participants, 57 % (n4) felt they could
not have maintained the TRF protocol beyond 10 weeks. This
was mainly due to incompatibility with family/social life, with
one participant noting that they found sticking to the TRF
regimen relatively easy as they lived alone. Of the participants,
43 % (n3) felt they would consider continuing the protocol if
it had demonstrable health benets or would consider con-
tinuing a more exible protocol, e.g. MondayFriday, earlier
dinners or later breakfasts/dinners. An important consider-
ation for future work is therefore the positioning of the
TRF window within the 24 h day, and whether the TRF win-
dow should remain constant or can vary.
Dietary intake
Consistent with other human studies
, the TRF interven-
tion also caused a decrease in daily energy intake despite ad libi-
tum food access, indicated by a signicant group × time
interaction (Fig. 1(b)). This was corroborated by questionnaire
responses, with 57 % (n4) of participants noting a reduction in
food intake either due to reduced appetite, reduced duration of
eating opportunities and/or reduced snacking (particularly in
the evening). Overall, daily energy intake distribution was
unaffected, as there was no signicant group × time interaction
at baseline (Fig. 1(c)) or intervention week 10 (Fig. 1(d)). Some
TRF participants reported eating less healthilyvia increased
consumption of convenience foods due to time restrictions
with food preparation (n3), whilst others consumed less alcohol
(n5), presumably due to reduced evening social opportunities,
although this did not translate into signicant between-group dif-
ferences in the changes in macronutrient intakes (Supplementary
Table S1). Analysis of diet diaries from participants who com-
pleted them at baseline, intervention week 5 and intervention
week 10 indicates that changes in dietary intake were similar
throughout the intervention period (Supplementary Fig. S1 and
Table S2).
Body weight
Despite the observed changes in energy intake, body weight
was not signicantly changed after either the control (from
SEM 7·5) to 77·3(SEM 7·7) kg; P=0·114) or TRF
(from 86·2(
SEM 5·2) to 85·5(SEM 5·2) kg; P=0·374)
interventions, and this was comparable between groups (P=
0·748; two-way repeated-measures ANOVA). Similarly, there
wasnosignicant interaction between assessment group × time
for BMI (P=0·788; two-way repeated-measures ANOVA).
The control group had BMI of 28·6(
SEM 2·8) and 28·4
(SEM 2·9) kg/m
, whereas the TRF group had BMI of 29·0
(SEM 1·7) and 28·7(SEM 1·8) kg/m
(baseline v. post-intervention,
In contrast to the body weight data, there was a signicant
(P=0·047; MannWhitney Utest) effect of dietary interven-
tion on percentage body fat (Fig. 2(a)). Indeed, all members
of the TRF group exhibited lower body fat by the end of
the intervention period (Fig. 2(c)), with an average reduction
of 1·9(
SEM 0·3) percentage points after TRF. Lean body
mass was not measured, and this may explain the discrepancy
in the body weight data, whereby net body weight remained
unchanged despite reductions in adiposity and food intake.
Despite this, the consistency of the observed reduction in adi-
posity among all TRF participants suggests that these data
represent a true treatment effect; nonetheless, replication is
required given the type 1 error risk.
One purported mechanism for the health benets of TRF is
that a higher percentage of energy is consumed during a restricted
phase of the endogenous circadian cycle. Additionally, TRF may
exert benets by increasing the length of the daily fast
However, given our participants consumed signicantly less
energy per d as a result of a TRF intervention (despite ad libitum
food access), this is likely to be a key driver of the observed
changes in adiposity
Fasting plasma biochemistry
Although there was no signicant difference in fasting plasma
glucose between the two groups during baseline conditions, a
signicant diet × group interaction was observed for the change
in fasting plasma glucose (Fig. 2(d)). This was largely driven by
elevated concentrations consistently observed among all partici-
pants in the control group at the end of the intervention period
but the reason for this change is unknown; given there were no
reported signicant changes in dietary intake in the control
group, this is suggestive of changes in other unknown factor(s).
There were modest changes in other metabolic disease
risk markers, including trends in favour of a reduction in
LDL-cholesterol; however these were not signicantly dif-
ferent from the control group (Fig. 2(e)(i)). This is per-
haps unsurprising given the small, healthy cohort studied.
Nonetheless, data provide valuable pilot information that
can be used to design appropriately powered future studies
that include assessment of metabolic physiology.
Strengths, weaknesses and impact on future experimental
The particular strengths of the present study include its controlled
study design and modest but achievable TRF protocol. By
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contrast, many published TRF-related studies lasted for a max-
imum of 4 weeks, involved extreme temporal restriction, or
included alternate TRF/non-TRF days; others are observational
Ramadan studies in which participants changed not only their
feeding duration but timing from a diurnal to nocturnal feeding
. Our exit questionnaire also provides insights into
the factors affecting the acceptability of TRF and how this
could be improved, for instance by reducing the number of
TRF days per week. TRF for 5 d per week has proved efcacious
in rodents in terms of reducing adiposityand improving metabolic
but the efcacy in humans remains to be established.
This pilot study did have limitations. The study was con-
ducted in a small group of both healthy and overweight
well-motivated, predominantly female, participants within a
high-income region in Surrey recruited as part of a television
documentary. This limits generalisability of the ndings to
other population groups and increases the risk of type 1 and
2 errors. Other limitations include the reliance upon self-
reported energy intakes and the use of bioimpedance to assess
changes in body composition. Whilst bioimpedance is validated
against more robust anthropometrical techniques such as
dual-energy X-ray absorptiometry, it does systematically under-
estimate body fat with increasing adiposity and can be inu-
enced by hydration and hormonal status
. Lastly, whilst
participants were asked to maintain habitual activity levels, no
formal monitoring of physical activity was conducted. It is
therefore unknown whether TRF led to compensatory changes
in physical activity, which would also inuence overall energy
balance. Although assessment of metabolic markers revealed
non-signicant changes in plasma TAG/cholesterol concentra-
tion, our data provide valuable insight into the magnitude and
variation of expected responses, which will inform experimen-
tal design and power calculations for future experiments.
In conclusion, data from this 10-week pilot study provide ini-
tial evidence that a modest contraction of the eating window is
achievable within a free-living human population. Moreover,
the TRF intervention elicited favourable changes in dietary
intakes, accompanied by a reduction in adiposity. The import-
ance of this unintentionaldietary modication is important in
the context of our obesogenic environment. However, partici-
pation in the study did affect social eating/drinking opportun-
ities in the evening. Larger studies are now required and, based
on our preliminary ndings, should also carefully consider per-
sonal/social considerations of participants undertaking TRF
protocols to maximise compliance.
40(a) (b) (c)
P = 0·047 P = 0·001 P = 0·305
P = 0·729P = 0·904P = 0·008
P = 0·068 P = 0·104 P = 0·702
(d) (e) (f)
(g) (h) (i)
% Body fat
% Body fat
% Body fat
Baseline Intervention Baseline Intervention Baseline Intervention
Baseline Intervention Baseline Intervention Baseline Intervention
Baseline Intervention Baseline Intervention Baseline Intervention
Glucose (mmol/l)Total cholesterol
TAG (mmol/l)
Insulin (µU/ml)
Fig. 2. Effect of time-restricted feeding (TRF) on body fat and fasting plasma markers. After a 2-week baseline period, participants maintained habitual feeding pat-
terns or restricted their daily feeding duration by 3 h for 10 weeks, with data collected at the end of the baseline and 10-week intervention periods. (a) Average per-
centage body fat in both groups at the end of the baseline and intervention periods. (b) and (c) Percentage body fat in each individual in the (b) TRF and (c) control
groups at the end of the baseline and intervention periods. (d)(i) Fasting plasma markers in both groups at the end of the baseline and intervention periods. –––,
Control group (n6); ---, TRF group (n7). In panels (b) and (c), data are individual values, Pvalues are within-group changes; in other panels, data are means, with
standard errors represented by vertical bars. Pvalues represent the group x time interactions.
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Supplementary material
The supplementary material for this article can be found at
The authors thank Leila Finikarides for recruitment and help
with study management and Dr Jo Sier for analysis of plasma
Financial support was received from the University of
Surrey and the British Broadcasting Corporation.
All authors conducted the experiment. R. A. analysed data
and wrote the manuscript; T. M. R. and M. D. R. revised the
manuscript; J. D. J. analysed data and wrote the manuscript.
J. D. J. has performed consultancy work for Kellogg
Marketing and Sales Company (UK) Limited, and collaborates
with the Nestlé Institute of Health Sciences.
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... Ten studies were randomized controlled trials [30, 33, 36, 41-43, 45, 48, 50, 51] of which one had a crossover design [51]. Ten studies were pilot studies [11,22,24,25,32,35,38,46,49,52]. Bjerre et al. [20,21] conducted a qualitative study in a subgroup of participants from a TRE intervention group [53]. ...
... One study prescribed an eating window that was longer than 10 hours [11]. The study by Antoni et al. [32] prescribed an eating window with a 3-hour reduction compared with the habitual eating window, by delaying the first energy intake and advancing the last energy intake of the day by 1.5 hours each. Two studies compared different lengths of eating windows [34,42], and two studies compared early and late TRE [43,45]. ...
... The actual eating window during TRE interventions was reported in 12 studies [22, 23, 25, 32, 33, 35, 38, 44-46, 49, 51], and it ranged between 6.5 h/d [45] and 11.9 h/d [38] (Table 3). Furthermore, 10 studies [11,23,32,33,38,43,45,46,49,50] reported that the average reduction in eating window compared with the habitual eating window ranged from À2.4 h/d [23] to À5.4 h/d [33] (Table 3). ...
Full-text available
Objective: This systematic scoping review aimed to map and synthesize research on feasibility of time-restricted eating (TRE) in individuals with overweight, obesity, prediabetes, or type 2 diabetes, including recruitment rate, retention rate, safety, adherence, and participants' attitudes, experiences, and perspectives. Methods: The authors searched MEDLINE, Embase, and Cumulative Index to Nursing and Allied Health Literature from inception to November 22, 2022, supplemented by backward and forward citation search. Results: From 4219 identified records, 28 studies were included. In general, recruitment was easy and median retention rate was 95% among studies with <12 weeks duration and 89% among studies ≥12 weeks. Median (range) adherence to the target eating window for studies <12 and ≥12 weeks was 89% (75%-98%) and 81% (47%-93%), respectively. Variation in adherence among participants and studies was considerable, indicating that following TRE was difficult for some people and that intervention conditions influenced adherence. These findings were supported by qualitative data synthetized from seven studies, and determinants of adherence included calorie-free beverages outside the eating window, provision of support, and influence on the eating window. No serious adverse events were reported. Conclusions: TRE is implementable, acceptable, and safe in populations with overweight, obesity, prediabetes, or type 2 diabetes, but it should be accompanied by support and options for individual adjustments.
... circumference in individuals with overweight and obesity [5][6][7][8][9][10][11], as well as fat mass in healthy-weight, resistance-trained males and females [12][13][14]. ...
... TRE has been demonstrated to result in weight loss ranging from 1% to 4% of body weight in studies lasting 4 weeks [15], 8 weeks [7], 12 weeks [6,8,11] and 16 weeks [9], with a concomitant reduction in daily energy intake of between~8% and~20% in studies allowing ad libitum eating [8,9]. Additionally, TRE may modify substrate oxidation, utilizing free fatty acids and fatty-acid derived ketones as energy by extending the fasting period to ≥12 h, leading to subsequent reductions in body adiposity [5,16,17]. Other TRE programs suggest there are cardiometabolic benefits associated with restricted eating, specifically in improving postprandial or 24 h mean glucose levels, fasting glucose, and insulin levels when early TRE (eTRE) is followed [18][19][20][21][22]. ...
... Moreover, the application of clinical methods may not be compatible within the reality of modern-day living. Research indicates that adherence to a diet is greater in studies when foods are provided within a clinical setting or available to take home [3][4][5]. This may partially explain why compliance rates of~98% were observed in a 5-week eTRE study wherein all meals were provided and consumed within a 6 h eating window between 9:00 and 15:00 h [21]. ...
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Whilst the treatment and prevention of overweight and obesity-related disease is managed by restricting daily energy intake, long-term adherence to dietary strategies appears unsustainable. Time-restricted eating (TRE) aims to position energy intake in an eating window under 12 h per day and offers an alternative behavioral intervention, which can aid weight management and improve cardiometabolic health. Adherence to previous TRE protocols is estimated at between 63 and 100%, although the accuracy of reporting is unclear. This study therefore aimed to provide an objective, subjective, and qualitative overview of adherence to a prescribed TRE protocol, and to identify any potential barriers affecting adherence. Adherence after 5 weeks of TRE was estimated at ~63% based on continuous glucose monitoring data when compared with time-stamped diet diaries. Subjective participant responses reported adherence at an average of ~61% per week. Barriers to adopting TRE, including work schedules, social events, and family life, were identified by participants during qualitative interviews. The findings of this study suggest that the development of personalized TRE protocols may help to navigate the barriers to adherence leading to improved health-related outcomes.
... Было доказано, что сбой этого регенеративного процесса может привести к нейродегенеративным заболеваниям, таким как болезнь Альцгеймера, болезнь Паркинсона, синдром Гентингтона, некоторым формам деменции и раку. Утверждалось также, что запустить аутофагию в клетках можно, придерживаясь различных схем периодического голодания [8,9]. ...
... Из-за массового апоптоза клеток разрушаются нуклеиновые кислоты их ядер, и растет выведение немочевинного азота. При голодании происходит ступенчатое изменение обмена веществ с характерными стадийными эндокринно-метаболическими изменениями и сменой основных энергетических субстратов [5,6,8,13]. ...
В настоящее время все больше приобретает популярность среди людей отказ от приема пищи в течение ограниченного времени. Однако сведения о воздействии голодания на состояние здоровья человека в настоящее время продолжают оставаться противоречивыми. В нашем эксперименте на примере молодого добровольца были показаны изменения нутритивного статуса, метаболического профиля и микробиоценоза кишечника на фоне полного голодания в течение 15 дней. Nowadays, it is becoming more and more popular among people to refuse to eat for a limited time. However, information about the impact of fasting on human health at the present time continues to be controversial. In our experiment, on the example of a young volunteer, changes in the nutritional status, metabolic profile and intestinal microbiocenosis were shown against the background of complete starvation for 15 days.
... overall beneficial trend of TRE on glycemic parameters (8,9,15,17,18,19,31,32,33,34,35,36,37,38), although these findings have not been universal (11,16,32,39,40,41,42,43,44,45,46,47,48,49,50,51). The improvements in fasting glucose, insulin resistance, and insulin sensitivity that have been observed in studies have often been attributed to calorie restriction and weight loss (8,31,46,52,53,54,55), though there are a handful of TRE trials that demonstrated a positive effect of TRE on glucose metabolism in the absence of significant changes in energy intake or weight (9,10,32,33,34,35,36,37). ...
... overall beneficial trend of TRE on glycemic parameters (8,9,15,17,18,19,31,32,33,34,35,36,37,38), although these findings have not been universal (11,16,32,39,40,41,42,43,44,45,46,47,48,49,50,51). The improvements in fasting glucose, insulin resistance, and insulin sensitivity that have been observed in studies have often been attributed to calorie restriction and weight loss (8,31,46,52,53,54,55), though there are a handful of TRE trials that demonstrated a positive effect of TRE on glucose metabolism in the absence of significant changes in energy intake or weight (9,10,32,33,34,35,36,37). The conflicting results of these studies may be related to variable timing and duration of eating windows, short duration of intervention, and small sample sizes in many of the studies. ...
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Background The median eating duration in the U.S. is 14.75 h, spread throughout the period of wakefulness and ending before sleep. Food intake at an inappropriate circadian time may lead to adverse metabolic outcomes. Emerging literature suggests that time restricted eating (TRE) may improve glucose tolerance and insulin sensitivity. The aim was to compare 24‐h glucose profiles and insulin sensitivity in participants after completing 12 weeks of a behavioral weight loss intervention based on early TRE plus daily caloric restriction (E‐TRE+DCR) or DCR alone. Methods Eighty‐one adults with overweight or obesity (age 18–50 years, BMI 25–45 kg/m ² ) were randomized to either E‐TRE+DCR or DCR alone. Each participant wore a continuous glucose monitor (CGM) for 7 days and insulin sensitivity was estimated using the homeostatic model assessment of insulin resistance (HOMA‐IR) at Baseline and Week 12. Changes in CGM‐derived measures and HOMA‐IR from Baseline to Week 12 were assessed within and between groups using random intercept mixed models. Results Forty‐four participants had valid CGM data at both time points, while 38 had valid glucose, insulin, HOMA‐IR, and hemoglobin A1c (A1c) data at both timepoints. There were no significant differences in sex, age, BMI, or the percentage of participants with prediabetes between the groups (28% female, age 39.2 ± 6.9 years, BMI 33.8 ± 5.7 kg/m ² , 16% with prediabetes). After adjusting for weight, there were no between‐group differences in changes in overall average sensor glucose, standard deviation of glucose levels, the coefficient of variation of glucose levels, daytime or nighttime average sensor glucose, fasting glucose, insulin, HOMA‐IR, or A1c. However, mean amplitude of glycemic excursions changed differently over time between the two groups, with a greater reduction found in the DCR as compared to E‐TRE+DCR ( p = 0.03). Conclusion There were no major differences between E‐TRE+DCR and DCR groups in continuous glucose profiles or insulin sensitivity 12 weeks after the intervention. Because the study sample included participants with normal baseline mean glucose profiles and insulin sensitivity, the ability to detect changes in these outcomes may have been limited.
... TRE allows ad libitum intake within the window without quality or quantity restrictions on foods or beverages. 9,10 Time-restricted eating has been highlighted as a tangible and simple strategy requiring less nutritional knowledge than other dietary interventions. 6,11 Among people at high risk of T2D, TRE has positive effects on body weight, glucose metabolism, and cardiometabolic health, 6,12,13 and it has been shown that TRE can improve glycemic control and reduce body weight and also be a safe strategy in people with overweight and T2D. ...
... 36,37 Other studies also emphasize that low levels of social support 11,38,40 and eating out in the evening with family or friends are barriers to successfully integrating TRE into daily life. 10,34,40 According to Antonovsky, 23 people with previous success at changing health behaviors would be at an advantage in performing TRE compared with those without such experiences. Indeed, life experiences leading to a strong SOC allow individuals to seek help and apply resources appropriate to a specific stressor, such as behavior change. ...
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Objective: To design an appealing time-restricted eating (TRE) intervention by exploring behavioral and social mechanisms to improve TRE adoption and maintenance among people with type 2 diabetes (T2D) and overweight. Time-restricted eating is an intermittent fasting regimen suggested to improve glycemic control and body weight. Methods: Intervention development combined coherence theory and empirical data (workshops and semistructured interviews with the target group, their relatives, and health care professionals [HCPs]). Abductive analysis was applied. Results: The analysis suggested designing the TRE intervention in 2 phases: a short period with strict TRE, followed by a longer period focusing on adapting TRE to individual needs with support from HCPs, relatives, and peers. To reinforce TRE motivation and maintenance, HCPs should adopt a whole-person approach that focuses on participants' previous experiences. Conclusions and implications: Important intervention elements to promote TRE adoption and maintenance are suggested to include a 2-phase design and support from professionals, family, and peers.
... Consistent with this study, Chow et al. [42] applied a limited diet of 8 h for 12 weeks and, while a 3.7% decrease in body weight of individuals was observed, no change was found in body fat percentages. In previous similar studies, body weight loss was observed in individuals [43][44][45][46], but contrary to this study, most of studies conducted showed a significant decrease in body fat percentages with loss of body weight in individuals [43,45,47,48]. On the other hand, in this study, significant reductions in waist circumference, waist/height ratio, BMI, visceral fat and abdominal fat are very important in terms of preventing obesity and related diseases, and the results suggest that TRE may be an effective dietary intervention for noncommunicable diseases. ...
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Background Time-restricted eating (TRE) is a current popular dietary strategy for noncommunicable diseases. However, studies demonstrated contradictory results for it and in all dietary strategies, diet quality is an the important part of the well-being. Our study aimed to investigate the effect of TRE and energy-restricted diet (ERD) on the nutritional status and diet quality of individuals. Methods This pilot study was completed 23 healthy overweight female. Anthropometric and body composition measurements of individuals were taken. The energy expenditure was measured using indirect calorimetry. Blood pressure and heart rate measurements were made. Biochemical parameters were evaluated and food consumption were taken. The quality of dietary intake was assessed using the Healthy Eating Index (HEI) -2015. The physical activity levels of the individuals were estimated using the physical activity record. The Statistical Package for the Social Sciences (version 22.0) software was used for all analyses. A p-value of less than 0.05 was considered to be statistically significant. Results After 8 weeks of intervention, while no change was observed in the diet quality of the individuals in the TRE group (p > 0.05), a significant increase was found in the diet quality score of the individuals in the ERD group (p < 0.05). There was a 3.2% and 5.5% decrease in body weight of individuals in the TRE and ERD groups, respectively (p < 0.05). While no significant change was observed in the body fat percentage of individuals in the TRE group (p > 0.05), a 7.1% decrease was observed in the ERD group (p < 0.05). A statistically significant decrease was found in the total cholesterol (3.7%) in the ERD group, and in the total cholesterol (6.7%) and low density lipoprotein cholesterol (LDL-C) (6.5%) in the TRE group. In addition, a statistically significant increase was found in adiponectin (77.3%) and total antioxidant status (TAS) (13.2%) in the ERD group. Conclusion Energy-restricted diet yielded better results in weight loss and improvement of body composition and diet quality compared to TRE. Also, a decrease in total cholesterol level was found in the ERD group. However, more studies should be done with longer follow-ups and high sample sizes are very important in terms of creating public health-based recommendations.
... Intake of water is possible/allowed [82]. TRF is known to improve health [79,[82][83][84][85]. ...
Lately, we've witnessed the emergence of obesity as a prominent concern for public health and the economy. This issue commands serious attention, impacting millions worldwide, particularly in the most developed nations. Practical approaches to tackling obesity involve tailored physical activity and dietary interventions overseen by qualified healthcare professionals. Nonetheless, some individuals opt for quicker routes, embracing dietary regimens that promise rapid and effortless weight reduction yet lack substantiated scientific backing. Given the potential hazards these approaches pose to well-being, this calls for immediate address, occasionally leading to unexpected and severe consequences. In this review, we aim to analyze the curiosities of popular diets embraced by adults from the 1960s to the present day, including the scientific justification that supports or contradicts their effectiveness.
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Background Time-restricted eating (TRE), a feasible form of intermittent fasting, has been proven to benefit metabolic health in animal models and humans. To our knowledge, specific guidance on the appropriate period for eating during TRE has not yet been promoted. Therefore, to compare and assess the relative effectiveness estimates and rankings of TRE with different eating windows on human metabolic health, we conducted a systematic review and network meta-analysis (NMA). Method PubMed, EMBASE and the Cochrane Library were searched for randomized controlled trials that compared different eating windows on human metabolic health for adults. A Bayesian NMA was used to compare direct and indirect effects to determine the best different eating windows, and scientific evidence using GRADE. Results Twenty-seven RCTs comparing TRE with different eating windows on human metabolic health were reviewed, and all were included in the NMA. Compared with the normal diet group (non-TRE), the TRE group has certain benefits in reducing weight and fasting insulin. In terms of reducing fasting insulin, the 18:6 group (eating time = 6 h) was better than the 14:10 group (eating time = 10 h) and 16:8 group (eating time = 8 h) (P < 0.05); The < 6 group (eating time < 6 h) was better than the 14:10 group (P < 0.05). In terms of reducing fasting glucose, the < 6 group was better than the 14:10 group (P < 0.05). There were no statistical variations in weight, HDL, TG, and LDL across the different modes of TRE (P > 0.05). Conclusions Our research showed that no particular metabolic advantages of various eating windows were found. Therefore, our results suggested that different eating windows could promote similar benefits for metabolic parameters.
Obesity is a chronic disease that increases morbidity and mortality and adversely affects quality of life. The rapid rise of obesity has outpaced the development and deployment of effective therapeutic interventions, thereby creating a global health crisis. The presentation, complications, and response to obesity treatments vary, yet lifestyle modification, which is the foundational therapeutic intervention for obesity, is often "one size fits all." The concept of personalized medicine uses genetic and phenotypic information as a guide for disease prevention, diagnosis, and treatment and has been successfully applied in diseases such as cancer, but not in obesity. As we gain insight into the pathophysiologic mechanisms of obesity and its phenotypic expression, specific pathways can be targeted to yield a greater, more sustained therapeutic impact in an individual patient with obesity. A phenotype-based pharmacologic treatment approach utilizing objective measures to classify patients into predominant obesity mechanism groups resulted in greater weight loss (compared with a non-phenotype-based approach) in a recent study by Acosta and colleagues. In this review, we discuss the application of lifestyle modifications, behavior therapy and pharmacotherapy using the obesity phenotype-based approach as a framework.
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Two intermittent fasting variants, intermittent energy restriction (IER) and time-restricted feeding (TRF), have received considerable interest as strategies for weight-management and/or improving metabolic health. With these strategies, the pattern of energy restriction and/or timing of food intake are altered so that individuals undergo frequently repeated periods of fasting. This review provides a commentary on the rodent and human literature, specifically focusing on the effects of IER and TRF on glucose and lipid metabolism. For IER, there is a growing evidence demonstrating its benefits on glucose and lipid homeostasis in the short-to-medium term; however, more long-term safety studies are required. Whilst the metabolic benefits of TRF appear quite profound in rodents, findings from the few human studies have been mixed. There is some suggestion that the metabolic changes elicited by these approaches can occur in the absence of energy restriction, and in the context of IER, may be distinct from those observed following similar weight-loss achieved via modest continuous energy restriction. Mechanistically, the frequently repeated prolonged fasting intervals may favour preferential reduction of ectopic fat, beneficially modulate aspects of adipose tissue physiology/morphology, and may also impinge on circadian clock regulation. However, mechanistic evidence is largely limited to findings from rodent studies, thus necessitating focused human studies, which also incorporate more dynamic assessments of glucose and lipid metabolism. Ultimately, much remains to be learned about intermittent fasting (in its various forms); however, the findings to date serve to highlight promising avenues for future research.
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Background Intermittent fasting (IF) is an increasingly popular dietary approach used for weight loss and overall health. While there is an increasing body of evidence demonstrating beneficial effects of IF on blood lipids and other health outcomes in the overweight and obese, limited data are available about the effect of IF in athletes. Thus, the present study sought to investigate the effects of a modified IF protocol (i.e. time-restricted feeding) during resistance training in healthy resistance-trained males. Methods Thirty-four resistance-trained males were randomly assigned to time-restricted feeding (TRF) or normal diet group (ND). TRF subjects consumed 100 % of their energy needs in an 8-h period of time each day, with their caloric intake divided into three meals consumed at 1 p.m., 4 p.m., and 8 p.m. The remaining 16 h per 24-h period made up the fasting period. Subjects in the ND group consumed 100 % of their energy needs divided into three meals consumed at 8 a.m., 1 p.m., and 8 p.m. Groups were matched for kilocalories consumed and macronutrient distribution (TRF 2826 ± 412.3 kcal/day, carbohydrates 53.2 ± 1.4 %, fat 24.7 ± 3.1 %, protein 22.1 ± 2.6 %, ND 3007 ± 444.7 kcal/day, carbohydrates 54.7 ± 2.2 %, fat 23.9 ± 3.5 %, protein 21.4 ± 1.8). Subjects were tested before and after 8 weeks of the assigned diet and standardized resistance training program. Fat mass and fat-free mass were assessed by dual-energy x-ray absorptiometry and muscle area of the thigh and arm were measured using an anthropometric system. Total and free testosterone, insulin-like growth factor 1, blood glucose, insulin, adiponectin, leptin, triiodothyronine, thyroid stimulating hormone, interleukin-6, interleukin-1β, tumor necrosis factor α, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides were measured. Bench press and leg press maximal strength, resting energy expenditure, and respiratory ratio were also tested. ResultsAfter 8 weeks, the 2 Way ANOVA (Time * Diet interaction) showed a decrease in fat mass in TRF compared to ND (p = 0.0448), while fat-free mass, muscle area of the arm and thigh, and maximal strength were maintained in both groups. Testosterone and insulin-like growth factor 1 decreased significantly in TRF, with no changes in ND (p = 0.0476; p = 0.0397). Adiponectin increased (p = 0.0000) in TRF while total leptin decreased (p = 0.0001), although not when adjusted for fat mass. Triiodothyronine decreased in TRF, but no significant changes were detected in thyroid-stimulating hormone, total cholesterol, high-density lipoprotein, low-density lipoprotein, or triglycerides. Resting energy expenditure was unchanged, but a significant decrease in respiratory ratio was observed in the TRF group. Conclusions Our results suggest that an intermittent fasting program in which all calories are consumed in an 8-h window each day, in conjunction with resistance training, could improve some health-related biomarkers, decrease fat mass, and maintain muscle mass in resistance-trained males.
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A randomized controlled trial was conducted to examine eight weeks of resistance training (RT) with and without time-restricted feeding (TRF) in order to assess nutrient intake and changes in body composition and muscular strength in young recreationally active males. The TRF programme consisted of consuming all calories within a four-hour period of time for four days per week, but included no limitations on quantities or types of foods consumed. The RT programme was performed three days per week and consisted of alternating upper and lower body workouts. For each exercise, four sets leading to muscular failure between 8 and 12 repetitions were employed. Research visits were conducted at baseline, four, and eight weeks after study commencement. Measurements of total body composition by dual-energy X-ray absorptiometry and muscle cross-sectional area by ultrasound were obtained. Upper and lower body strength and endurance were assessed, and four-day dietary records were collected. TRF reduced energy intake by ∼650 kcal per day of TRF, but did not affect total body composition within the duration of the study. Cross-sectional area of the biceps brachii and rectus femoris increased in both groups. Effect size data indicate a gain in lean soft tissue in the group that performed RT without TRF (+2.3 kg, d = 0.25). Upper and lower body strength and lower body muscular endurance increased in both groups, but effect sizes demonstrate greater improvements in the TRF group. Overall, TRF reduced energy intake and did not adversely affect lean mass retention or muscular improvements with short-term RT in young males.
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Chrononutrition is an emerging discipline that builds on the intimate relation between endogenous circadian (24-h) rhythms and metabolism. Circadian regulation of metabolic function can be observed from the level of intracellular biochemistry to whole-organism physiology and even postprandial responses. Recent work has elucidated the metabolic roles of circadian clocks in key metabolic tissues, including liver, pancreas, white adipose, and skeletal muscle. For example, tissue-specific clock disruption in a single peripheral organ can cause obesity or disruption of whole-organism glucose homeostasis. This review explains mechanistic insights gained from transgenic animal studies and how these data are being translated into the study of human genetics and physiology. The principles of chrononutrition have already been demonstrated to improve human weight loss and are likely to benefit the health of individuals with metabolic disease, as well as of the general population. Adv Nutr 2016;7:399–406.
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Because current therapeutics for obesity are limited and only offer modest improvements, novel interventions are needed. Preventing obesity with time-restricted feeding (TRF; 8-9 hr food access in the active phase) is promising, yet its therapeutic applicability against preexisting obesity, diverse dietary conditions, and less stringent eating patterns is unknown. Here we tested TRF in mice under diverse nutritional challenges. We show that TRF attenuated metabolic diseases arising from a variety of obesogenic diets, and that benefits were proportional to the fasting duration. Furthermore, protective effects were maintained even when TRF was temporarily interrupted by ad libitum access to food during weekends, a regimen particularly relevant to human lifestyle. Finally, TRF stabilized and reversed the progression of metabolic diseases in mice with preexisting obesity and type II diabetes. We establish clinically relevant parameters of TRF for preventing and treating obesity and metabolic disorders, including type II diabetes, hepatic steatosis, and hypercholesterolemia. Copyright © 2014 Elsevier Inc. All rights reserved.
Intermittent fasting (IF) improves cardiometabolic health; however, it is unknown whether these effects are due solely to weight loss. We conducted the first supervised controlled feeding trial to test whether IF has benefits independent of weight loss by feeding participants enough food to maintain their weight. Our proof-of-concept study also constitutes the first trial of early time-restricted feeding (eTRF), a form of IF that involves eating early in the day to be in alignment with circadian rhythms in metabolism. Men with prediabetes were randomized to eTRF (6-hr feeding period, with dinner before 3 p.m.) or a control schedule (12-hr feeding period) for 5 weeks and later crossed over to the other schedule. eTRF improved insulin sensitivity, β cell responsiveness, blood pressure, oxidative stress, and appetite. We demonstrate for the first time in humans that eTRF improves some aspects of cardiometabolic health and that IF's effects are not solely due to weight loss.
Most animals alternate periods of feeding with periods of fasting often coinciding with sleep. Upon >24 hr of fasting, humans, rodents, and other mammals enter alternative metabolic phases, which rely less on glucose and more on ketone body-like carbon sources. Both intermittent and periodic fasting result in benefits ranging from the prevention to the enhanced treatment of diseases. Similarly, time-restricted feeding (TRF), in which food consumption is restricted to certain hours of the day, allows the daily fasting period to last >12 hr, thus imparting pleiotropic benefits. Understanding the mechanistic link between nutrients and the fasting benefits is leading to the identification of fasting-mimicking diets (FMDs) that achieve changes similar to those caused by fasting. Given the pleiotropic and sustained benefits of TRF and FMDs, both basic science and translational research are warranted to develop fasting-associated interventions into feasible, effective, and inexpensive treatments with the potential to improve healthspan.
A diurnal rhythm of eating-fasting promotes health, but the eating pattern of humans is rarely assessed. Using a mobile app, we monitored ingestion events in healthy adults with no shift-work for several days. Most subjects ate frequently and erratically throughout wakeful hours, and overnight fasting duration paralleled time in bed. There was a bias toward eating late, with an estimated <25% of calories being consumed before noon and >35% after 6 p.m. "Metabolic jetlag" resulting from weekday/weekend variation in eating pattern akin to travel across time zones was prevalent. The daily intake duration (95% interval) exceeded 14.75 hr for half of the cohort. When overweight individuals with >14 hr eating duration ate for only 10-11 hr daily for 16 weeks assisted by a data visualization (raster plot of dietary intake pattern, "feedogram") that we developed, they reduced body weight, reported being energetic, and improved sleep. Benefits persisted for a year.
Time-restricted feeding (TRF), a key component of intermittent fasting regimens, has gained considerable attention in recent years. TRF allows ad libitum energy intake within controlled time frames, generally a 3–12 hour range each day. The impact of various TRF regimens on indicators of metabolic disease risk has yet to be investigated. Accordingly, the objective of this review was to summarize the current literature on the effects of TRF on body weight and markers of metabolic disease risk (i.e., lipid, glucoregulatory, and inflammatory factors) in animals and humans. Results from animal studies show TRF to be associated with reductions in body weight, total cholesterol, and concentrations of triglycerides, glucose, insulin, interleukin 6, and tumor necrosis factor-α as well as with improvements in insulin sensitivity. Human data support the findings of animal studies and demonstrate decreased body weight (though not consistently), lower concentrations of triglycerides, glucose, and low-density lipoprotein cholesterol, and increased concentrations of high-density lipoprotein cholesterol. These preliminary findings show promise for the use of TRF in modulating a variety of metabolic disease risk factors.