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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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BRIEF REPORT
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
Abstract
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
2
) 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
(1)
. One consequence of metabolic rhythms is the
interaction between time of day and food intake (chrononutri-
tion)
(2)
. An emerging area of chrononutrition is time-restricted
feeding (TRF), in which the daily duration of food intake is
shortened
(3)
. TRF reduces animalsbody weight and improves
markers of metabolic health without altered energy consump-
tion
(4,5)
.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
(6)
.
In humans 24 h rhythms of glucose homeostasis and post-
prandial responses are well known
(79)
, 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
(10,11)
.
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 r.antoni@surrey.ac.uk
© The Author(s) 2018. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creative-
commons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is
properly cited.
JNS
JOURNAL OF NUTRITIONAL SCIENCE
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Methods
Participants
Sixteen healthy participants (BMI 2039 kg/m
2
) 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
(12)
,
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
2
)29·01·728·62·8
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
(13)
. Intra-assay
CV were <5 %.
Questionnaire
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?.
Statistics
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
2
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
intervention
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
(14,15)
.
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
(1618)
, 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
77·8(
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
2
, whereas the TRF group had BMI of 29·0
(SEM 1·7) and 28·7(SEM 1·8) kg/m
2
(baseline v. post-intervention,
respectively).
Adiposity
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
(19)
.
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
(1618)
.
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
design
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
pattern
(10,11)
. 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
markers
(6)
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
(20)
. 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.
Conclusion
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
35
30
5·5
5·0
4·5
4·0
3·5
10
8
6
4
2
0
4·5
4·0
3·5
3·0
2·5
6·0
5·5
5·0
4·5
4·0
3·5
2·0
1·6
1·4
1·2
1·0
0·8
1·5
1·0
0·5
0
30
40
50
(d) (e) (f)
(g) (h) (i)
20
30
40
50
20
% 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
(mmol/l)
LDL-cholesterol
(mmol/l)
HDL-cholesterol
(mmol/l)
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.
5
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Supplementary material
The supplementary material for this article can be found at
https://doi.org/10.1017/jns.2018.13
Acknowledgements
The authors thank Leila Finikarides for recruitment and help
with study management and Dr Jo Sier for analysis of plasma
samples.
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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journals.cambridge.org/jns
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... Additionally, prospective studies evaluating the effects of TRE on weight loss have either used self-selected eating windows (1)(2)(3)7,9) or have prescribed eating windows using arbitrary clock times, without considering individual differences in habitual sleep schedules (4,5,8). The use of self-selected eating windows in these studies presumes that early eating windows would be difficult to adhere to because of the typically later timing of social eating occasions. ...
... The use of self-selected eating windows in these studies presumes that early eating windows would be difficult to adhere to because of the typically later timing of social eating occasions. These trials have shown modest weight loss (1%-4%) over 8 to 26 weeks (1)(2)(3)(4)(5)(6)(7)(8)(9). However, none of these studies has included recommendations on caloric restriction or provided the support of a behavioral weight-loss intervention (standard of care) (26). ...
... Therefore, this randomized, parallel-design trial was designed to assess the acceptability and efficacy of a 39-week behavioral weight-loss intervention using E-TRE (10-hour window starting within 3 hours of waking) plus DCR compared with DCR without time restriction in adults with overweight and obesity. We recommended caloric restriction to both groups owing to prior findings of only modest weight loss (1%-4%) in trials of TRE without caloric restriction (1)(2)(3)(4)(5)(6)(7)(8)(9). We chose a 10-hour eating window because of data from Gill and Panda (1) that showed that restricting EI to 10 to 11 h/d resulted in weight loss in humans. ...
Article
Objective: This trial aimed to evaluate the acceptability and efficacy of early time-restricted eating plus daily caloric restriction (E-TRE+DCR) compared with DCR alone within a behavioral weight-loss intervention. Methods: Participants (n = 81, 69 women, mean [SD] age: 38.0 [7.8] years, BMI: 34.1 [5.7] kg/m2 ) were randomized to E-TRE (10-hour eating window starting within 3 hours of waking) plus DCR or DCR alone (~35% DCR) for 39 weeks. The primary outcome was body weight (measured with digital scale) at week 12. Secondary outcomes measured at week 12 included hemoglobin A1c, lipids, energy intake (photographic food records), physical activity (accelerometry), dietary adherence (questionnaires), and body composition (dual-energy x-ray absorptiometry). Weight and body composition were also assessed at week 39. Results: Mean [SD] weight loss was not different between groups at week 12 (E-TRE+DCR: -6.2 [4.1] kg vs. DCR: -5.1 [3.2] kg) or at week 39 (E-TRE: -4.9 [5.3] kg vs. DCR: -4.3 [5.3] kg). There were no between-group differences in changes in body composition, dietary adherence, energy intake, physical activity, hemoglobin A1c, or lipids at week 12. Conclusions: E-TRE+DCR was found to be an acceptable dietary strategy, resulting in similar levels of adherence and weight loss compared with DCR alone.
... Notably, TRE is an easy to use dietary approach, because it does not require extensive nutritional knowledge and control of food quantity and quality. Most human TRE studies reported modest reduction of body weight (41,(47)(48)(49)(50)(51)(52)(53)(54)(55)(56)(57)(58)(59), fat mass (47,49,51,52,54,56,57,59), and waist circumference (53,54). Further beneficial effects of TRE are elevated adiponectin levels (52,56), decreased levels of inflammatory (52) and oxidative stress (51, 60) markers, lowered blood pressure (50,54,56,60), and even improvement in sleep quality and quality of life (41,53). ...
... Notably, TRE is an easy to use dietary approach, because it does not require extensive nutritional knowledge and control of food quantity and quality. Most human TRE studies reported modest reduction of body weight (41,(47)(48)(49)(50)(51)(52)(53)(54)(55)(56)(57)(58)(59), fat mass (47,49,51,52,54,56,57,59), and waist circumference (53,54). Further beneficial effects of TRE are elevated adiponectin levels (52,56), decreased levels of inflammatory (52) and oxidative stress (51, 60) markers, lowered blood pressure (50,54,56,60), and even improvement in sleep quality and quality of life (41,53). ...
... Further beneficial effects of TRE are elevated adiponectin levels (52,56), decreased levels of inflammatory (52) and oxidative stress (51, 60) markers, lowered blood pressure (50,54,56,60), and even improvement in sleep quality and quality of life (41,53). TRE has also shown to improve fasting glucose and postprandial glucose levels (49,52,59,61), mean daily glucose (58,61), and insulin resistance (51,52,55,60,61), as well as blood triglyceride (47,49,52,58,62), total cholesterol, and LDL cholesterol levels (54,62). However, the observed effects of TRE are highly variable and particularly contradictory, especially concerning metabolic outcomes. ...
Article
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Background: Time-restricted eating is a promising dietary strategy for weight loss, glucose and lipid metabolism improvements, and overall well-being. However, human studies demonstrated contradictory results for the restriction of food intake to the beginning (early TRE, eTRE) or to the end of the day (late TRE, lTRE) suggesting that more carefully controlled studies are needed. Objective: The aim of the ChronoFast trial study is to determine whether eTRE or lTRE is a better dietary approach to improve cardiometabolic health upon minimized calorie deficits and nearly stable body weight. Methods: Here, we present the study protocol of the randomized cross-over ChronoFast clinical trial comparing effects of 2 week eTRE (8:00 to 16:00 h) and lTRE (13:00 to 21:00 h) on insulin sensitivity and other glycemic traits, blood lipids, inflammation, and sleep quality in 30 women with overweight or obesity and increased risk of type 2 diabetes. To ensure timely compliance and unchanged dietary composition, and to minimize possible calorie deficits, real-time monitoring of dietary intake and body weight using a smartphone application, and extensive nutritional counseling are performed. Continuous glucose monitoring, oral glucose tolerance test, 24 h activity tracking, questionnaires, and gene expression analysis in adipose tissue and blood monocytes will be used for assessment of study outcomes. Discussion: The trial will determine whether eTRE or lTRE is more effective to improve cardiometabolic health, elucidate underlying mechanisms, and contribute to the development of recommendations for medical practice and the wider population. Clinical Trial Registration: www.ClinicalTrials.gov , Identifier [NCT04351672]
... Shifting light-dark cycles curtails fertility competence in mice [3][4][5][6] . Recently, dietary strategies that focus on the timing of eating and duration of fasting (i.e., chrono-nutrition) have been shown to improve metabolic health in humans 7,8 . Specifically, time-restricted feeding (TRF) limiting food access within the active phase is a dietary strategy that has emerged as a practical intervention for improving insulin resistance along with other markers of whole-body health 1,[7][8][9][10][11] . ...
... Recently, dietary strategies that focus on the timing of eating and duration of fasting (i.e., chrono-nutrition) have been shown to improve metabolic health in humans 7,8 . Specifically, time-restricted feeding (TRF) limiting food access within the active phase is a dietary strategy that has emerged as a practical intervention for improving insulin resistance along with other markers of whole-body health 1,[7][8][9][10][11] . However, there is a question whether chrono-nutrition also affects the fertility competence in females (animals or human) especially oocyte quality and quantity. ...
Article
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We assessed the effects of feeding regimen (ad libitum vs. time-restricted food access) and type of food (normal chow (NC: 12% fat) vs. moderately high calorie diet (mHCD: 31% fat)) on fertility competence of female mice. Mice fed mHCD had higher number of oocytes than mice fed NC. On the other hand, when mice were fed NC under time-restricted access to food (NT), the developmental rate to the blastocyst per number of normally fertilized ova was significantly decreased compared to others. The reactive oxygen species (ROS) level in oocytes increased in time-restricted food access and NC group. Transcriptome analysis of whole ovarian tissues from these mice showed a change in the cholesterol metabolism among the four groups. Time-restricted food access decreased serum LDL cholesterol level in both NC and mHCD groups. Moreover, the number of atretic follicles increased in NT mice compared to ad libitum food access mice. The present study shows that mHCD feeding increases the number of ovulated oocytes and that time-restricted feeding of NC impairs the developmental competence of oocytes after fertilization, probably due to the changes in serum cholesterol levels and an increase in the ROS content in oocytes.
... Other studies have reported even higher rates of adherence, including 98% adherence to five weeks of TRE in one small study of 8 men with prediabetes [62]. Furthermore, dropout rates from TRE studies are lower than in other formats of intermittent fasting (~10 vs. 20%) and much lower than caloric restriction (up to 33%) [128]. While it is likely that the lower dropout rate from studies would translate to greater real-world adherence, there is no research evidence to-date to confirm that TRE is associated with long-term adherence. ...
... The primary barriers to longer-term adherence to TRE include incompatibility with family/social life and work schedules [98]. One potential solution suggested by patients who had followed TRE was allowing a more flexible protocol (e.g., weekends off, customized eating window) [128]. Animal data suggest that time-restricted feeding during the week with ad libitum weekend feeding (even with access to high fat and sugar) is similarly effective to continuous (every day) time-restricted feeding for reducing fat mass, improving insulin resistance and normalizing triglyceride levels [129]. ...
Article
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There is substantial overlap in risk factors for the pathogenesis and progression of breast cancer (BC) and cardiovascular disease (CVD), including obesity, metabolic disturbances, and chronic inflammation. These unifying features remain prevalent after a BC diagnosis and are exacerbated by BC treatment, resulting in elevated CVD risk among survivors. Thus, therapies that target these risk factors or mechanisms are likely to be effective for the prevention or progression of both conditions. In this narrative review, we propose time-restricted eating (TRE) as a simple lifestyle therapy to address many upstream causative factors associated with both BC and CVD. TRE is simple dietary strategy that typically involves the consumption of ad libitum energy intake within 8 h, followed by a 16-h fast. We describe the feasibility and safety of TRE and the available evidence for the impact of TRE on metabolic, cardiovascular, and cancer-specific health benefits. We also highlight potential solutions for overcoming barriers to adoption and adherence and areas requiring future research. In composite, we make the case for the use of TRE as a novel, safe, and feasible intervention for primary and secondary BC prevention, as well as tertiary prevention as it relates to CVD in BC survivors.
... Similar findings have been reported previously in different animal strains with TRF [17,36,37]. In addition, these findings in animal models are similar to those reported by studies in obese humans who underwent TRF [9,38], although a few studies failed to show this effect [39,40]. In the present study, TRF with both a HFD and a standard diet for six weeks significantly reduced BMI and Lee's index in obese rats compared to those in control obese rats. ...
Article
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Obesity, where there is enhancement of stored body fat in adipose tissues, is associated with cardiovascular complications that are mainly related to atherosclerosis. Time-restricted feeding (TRF) is a form of restricted eating aimed at reducing weight in obese subjects. The present study aims to investigate changes in vascular endothelial function, endothelial nitric oxide synthase (eNOS), and protein kinase B (Akt) protein expressions with TRF in obese and normal rats. Male Sprague Dawley rats were divided into two normal and three obese groups; obesity was induced in the obese groups by feeding with a high-fat diet (HFD) for six weeks. After six weeks, rats were equally divided into five groups (n = 7 per group): Normal group (NR) which continued on a standard diet for six more weeks, normal group switched to TRF with a standard diet for six weeks (NR + TRFSD), obese group (OR) which continued on HFD for six more weeks, obese group switched to TRF of HFD (OR + TRFHFD), and obese group switched to TRF of a standard diet (OR + TRFSD). TRF was practiced for six weeks, after which the rats were sacrificed. Aortic endothelium-dependent and endothelium-independent relaxations and contractions were assessed using the organ bath. Aortic eNOS and Akt protein expressions were determined using immunoblotting. Fasting blood glucose, body weight, body mass index (BMI), serum lipid profile, Lee’s index, serum insulin levels, and sensitivity (HOMA-IR) were also measured. Endothelium-dependent relaxation was significantly impaired, while endothelium-dependent contraction increased in obese rats compared to that in normal rats. Both obese groups which underwent TRF with a HFD and standard diet improved their impairments in endothelium-dependent relaxation and reduced endothelium-dependent contraction; these were associated with increased expressions of aortic eNOS and Akt protein. Both obese groups with TRF reduced body weight, BMI, Lee’s index, total cholesterol, triglycerides, low-density lipoprotein cholesterol, and improved insulin sensitivity. TRF improved endothelium-dependent relaxation and reduced endothelium-dependent contraction, thus attenuating endothelial dysfunction in obese rats. These were associated with increased aortic eNOS and Akt protein expressions.
... The IER diet has a beneficial effect on LDL by increasing its particle size, which is important for reducing cardiovascular risk, as a small particle size has more proatherogenic, prothrombotic, and proinflammatory properties [70,71]. Both 10 weeks of TRE among patients with metabolic syndrome [46] and 12 weeks of TRE among overweight patients [72] decreased the LDL concentration. However, there are contradicting data; in some cases, IER regimens did not influence the LDL level, as when Sutton et al. presented the results of a five-week TRE diet among obese or overweight men with prediabetes [73]. ...
Article
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Obesity is a disease defined by an elevated body mass index (BMI), which is the result of excessive or abnormal accumulation of fat. Dietary intervention is fundamental and essential as the first-line treatment for obese patients, and the main rule of every dietary modification is calorie restriction and consequent weight loss. Intermittent energy restriction (IER) is a special type of diet consisting of intermittent pauses in eating. There are many variations of IER diets such as alternate-day fasting (ADF) and time-restricted feeding (TRF). In the literature, the IER diet is known as an effective method for bodyweight reduction. Furthermore, IER diets have a beneficial effect on systolic or diastolic pressure, lipid profile, and glucose homeostasis. In addition, IER diets are presented as being as efficient as a continuous energy restriction diet (CER) in losing weight and improving metabolic parameters. Thus, the IER diet could present an alternative option for those who cannot accept a constant food regimen.
... The beneficial effects regarding glycemic control appear more evident in early (between 8 a.m. and 2 p.m.) TRE (eTRE). Studies showed that eTRE improves whole-body insulin sensitivity, increases skeletal muscle glucose uptake, reduces 24-h glucose levels, and improves lipid metabolism, regardless of caloric restriction or weight loss [54,55,58,[64][65][66]. This result reported to be due to a significant increase of adiponectin [67]. ...
Article
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In recent years, a healthy balanced diet together with weight reduction has risen to the forefront of minimizing the impact of cardiovascular disease. There is evidence that metabolic processes present circadian rhythmicity. Moreover, the timing of food consumption exerts a powerful influence on circadian rhythms. In this context, the subject of chrononutrition, described as the alignment of timing of food intake to the rhythms imposed by the circadian clock, has attracted considerable interest for possible beneficial effects on cardiovascular health. Current human studies suggest that chrononutrition-based dietary interventions could reduce the risk for cardiovascular disease by improving weight control, hypertension, dyslipidemia, and diabetes. However, meta-analysis of randomized control trials in this topic present varying and somehow conflicting results. Even the traditional association of breakfast skipping with adverse cardiovascular outcomes is nowadays controversial. Therefore, long-term and fairly consistent studies on the effect of chrononutrition on cardiovascular outcomes are needed. The purpose of this review is to provide concise evidence of the most recent literature involving the effects of chrononutrition and the specific chrononutrition-based dietary interventions, in particular time-restricted eating, on body weight and other cardiovascular disease risk factors.
... During fasting times (7pm-7am), participants will be allowed to drink water, black tea or coffee, or other non-energy containing fluids. A milder 12-h TRF protocol is adopted in this study because it is deemed more aligned to normal social schedule and therefore easier to sustain [38,39]. Furthermore, it may provide a safer practice with regards to glycaemic control for patients with T2DM. ...
Article
Background and Aims Substantial scientific evidence supports the effectiveness of a Mediterranean diet (MedDiet) in managing type 2 diabetes mellitus (T2DM). Potential benefits of time restricted feeding (TRF) in T2DM are unknown. The MedDietFast trial aims to investigate the efficacy of a MedDiet with or without TRF compared to standard care diet in managing T2DM. Methods and Results 120 adults aged 20 -75 with a body mass index (BMI) of 20-35 kg/m² and T2DM will be randomised in a 3-arm parallel design to follow an ad libitum MedDiet with or without 12-hours TRF or the standard Australian Dietary Guidelines (ADG) for 24 weeks. All groups will receive dietary counselling fortnightly for 12 weeks and monthly thereafter. The primary outcome is changes in HbA1c from baseline to 12 and 24 weeks. Secondary outcomes include fasting blood glucose, insulin, blood lipids, weight loss, insulin resistance index (HOMA), Glucagon-like peptide 1 (GLP-1) and high-sensitivity C- reactive protein (hs-CRP). Data on medical history, anthropometry, wellbeing, MedDiet adherence and satiety will be measured at a private clinic via self-report questionnaires at baseline, 6, 12 and 24 weeks. Additionally, specimens (blood, urine and stool) will be collected at all time points for future omics analysis. Conclusion The MedDietFast trial will examine the feasibility and effectiveness of a MedDiet with/without TRF in T2DM patients. Potential synergistic effects of a MedDiet with TRF will be evaluated. Future studies will generate microbiomic and metabolomic data for translation of findings into simple and effective management plans for T2DM patients. Trial registration Australia and New Zealand Clinical Trials Register, ACTRN12619000246189;
Article
Time-restricted eating (TRE)¹ has been conceptualised as a strategy for achieving weight loss and improving metabolic health, but limited knowledge exists about how people can maintain TRE in daily life. This study examined how TRE was maintainable in daily life after a three-month intervention (the RESET study) in which participants were encouraged to consume all food and beverages except water within a 10-hour daily window. Specifically, we examined TRE maintenance patterns across participants, including drivers and challenges for maintenance success. A qualitative longitudinal study was conducted, and twenty participants with overweight at high risk of type 2 diabetes were interviewed using a semi-structured interview guide at the end of the intervention and after a three-month follow-up period. Data were analysed longitudinally in two steps inspired by a pattern-oriented longitudinal analysis approach. Seven participants maintained a strict 10-hour window, ten maintained an adjusted TRE regimen (e.g., taking days off), and three did not attempt maintenance. Maintenance drivers included consistent daily rhythms and regular meal patterns, subjective experiences (e.g., feeling healthier), making flexible adjustments to the TRE regimen, family support and avoiding feelings of guilt. Maintenance challenges included social evening events, inconsistent daily rhythms and eating patterns, preoccupation with losing weight, lack of family support and self-blame. TRE was manageable for most participants; however, personalised support for adjusting TRE to daily life is needed to ensure long-term maintenance. Future studies should explore the effectiveness of a personalised TRE concept to determine the usefulness of TRE in real-life settings.
Article
The quality and quantity of nutrition impact health. However, chrononutrition, the timing, and variation of food intake in relation to the daily sleep-wake cycle are also important contributors to health. This has necessitated an urgent need to measure, analyze, and optimize eating patterns to improve health and manage disease. While written food journals, questionnaires, and 24-hour dietary recalls are acceptable methods to assess the quantity and quality of energy consumption, they are insufficient to capture the timing and day-to-day variation of energy intake. Smartphone applications are novel methods for information-dense real-time food and beverage tracking. Despite the availability of thousands of commercial nutrient apps, they almost always ignore eating patterns, and the raw real-time data is not available to researchers for monitoring and intervening in eating patterns. Our lab developed a smartphone app called myCircadianClock (mCC) and associated software to enable long-term real-time logging that captures temporal components of eating patterns. The mCC app runs on iOS and android operating systems and can be used to track multiple cohorts in parallel studies. The logging burden is decreased by using a timestamped photo and annotation of the food/beverage being logged. Capturing temporal data of consumption in free-living individuals over weeks/months has provided new insights into diverse eating patterns in the real world. This review discusses (1) chrononutrition and the importance of understanding eating patterns, (2) the myCircadianClock app, (3) validation of the mCC app, (4) clinical trials to assess the timing of energy intake, and (5) strengths and limitations of the mCC app.
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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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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.
Article
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.
Article
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.
Article
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.
Article
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.
Article
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.