High-intensity intermittent exercise attenuates ad-libitum energy intake.
ABSTRACT Objective:To examine the acute effects of high-intensity intermittent exercise (HIIE) on energy intake, perceptions of appetite and appetite-related hormones in sedentary, overweight men.Design:Seventeen overweight men (body mass index: 27.7±1.6 kg m(-2); body mass: 89.8±10.1 kg; body fat: 30.0±4.3%; VO2peak: 39.2±4.8 ml kg(-1) min(-1)) completed four 30-min experimental conditions using a randomised counterbalanced design. CON: resting control, MC: continuous moderate-intensity exercise (60% VO2peak), HI: high-intensity intermittent exercise (alternating 60 s at 100% VO2peak and 240 s at 50% VO2peak), VHI: very-high-intensity intermittent exercise (alternating 15 s at 170% VO2peak and 60 s at 32% VO2peak). Participants consumed a standard caloric meal following exercise/CON and an ad-libitum meal 70 min later. Capillary blood was sampled and perceived appetite assessed at regular time intervals throughout the session. Free-living energy intake and physical activity levels for the experimental day and the day after were also assessed.Results:Ad-libitum energy intake was lower after HI and VHI compared with CON (P=0.038 and P=0.004, respectively), and VHI was also lower than MC (P=0.028). Free-living energy intake in the subsequent 38 h remained less after VHI compared with CON and MC (P0.050). These observations were associated with lower active ghrelin (P0.050), higher blood lactate (P0.014) and higher blood glucose (P0.020) after VHI compared with all other trials. Despite higher heart rate and ratings of perceived exertion (RPE) during HI and VHI compared with MC (P0.004), ratings of physical activity enjoyment were similar between all the exercise trials (P=0.593). No differences were found in perceived appetite between trials.Conclusions:High-intensity intermittent exercise suppresses subsequent ad-libitum energy intake in overweight inactive men. This format of exercise was found to be well tolerated in an overweight population.International Journal of Obesity advance online publication, 9 July 2013; doi:10.1038/ijo.2013.102.
- SourceAvailable from: Peter W R Lemon[Show abstract] [Hide abstract]
ABSTRACT: Data on whether sprint interval training (SIT) (repeated supermaximal intensity, short-duration exercise) affects body composition are limited, and the data that are available suggest that men respond more favourably than do women. Moreover, most SIT data involve cycling exercise, and running may differ because of the larger muscle mass involved. Further, running is a more universal exercise type. This study assessed whether running SIT can alter body composition (air displacement plethysmography), waist circumference, maximal oxygen consumption, peak running speed, and (or) the blood lipid profile. Fifteen recreationally active women (age, 22.9 ± 3.6 years; height, 163.9 ± 5.1 cm; mass, 60.8 ± 5.2 kg) completed 6 weeks of running SIT (4 to 6, 30-s "all-out" sprints on a self-propelled treadmill separated by 4 min of rest performed 3 times per week). Training decreased body fat mass by 8.0% (15.1 ± 3.6 to 13.9 ± 3.4 kg, P = 0.002) and waist circumference by 3.5% (80.1 ± 4.2 to 77.3 ± 4.4 cm, P = 0.048), whereas it increased fat-free mass by 1.3% (45.7 ± 3.5 to 46.3 ± 2.9 kg, P = 0.05), maximal oxygen consumption by 8.7% (46 ± 5 to 50 ± 6 mL/(kg·min), P = 0.004), and peak running speed by 4.8% (16.6 ± 1.7 to 17.4 ± 1.4 km/h, P = 0.026). There were no differences in food intake assessed by 3-day food records (P > 0.329) or in blood lipids (P > 0.595), except for a slight decrease in high-density lipoprotein concentration (1.34 ± 0.28 to 1.24 ± 0.24 mmol/L, P = 0.034). Running SIT is a time-efficient strategy for decreasing body fat while increasing aerobic capacity, peak running speed, and fat-free mass in healthy young women.Applied Physiology Nutrition and Metabolism 03/2014; 39(8):1-7. · 2.01 Impact Factor
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ABSTRACT: The present study assessed children’s appetite after consumption of either a low-calorie (LC) or high-calorie (HC) meal, followed by a timed bout of physical activity. Children aged six to ten years (N=19) participated in each of two trials, where they were asked to consume a HC or LC meal, and were then given free-choice access to physical and sedentary activities for 30 minutes. Trials were separated by one week, and treatment order of meals was randomized. The two, fast food-style meal conditions were comprised of the same food items and identical in macronutrient proportion, however were designed to contain approximately twice as much energy in the HC (~ 600 calories) compared to LC (~ 300 calories) condition. Subjective satiety ratings were collected via Visual Analogue Scale (VAS) at four time points during each trial (pre-meal, post-meal, post-activity, and four hours post-meal). ANOVA revealed a meal condition by time interaction (p = 0.045) for Appetite rating. Compared to HC, Appetite ratings were greater (p ≤ 0.015) in LC both immediately post-meal (71 ± 74, HC versus 131 ± 96, LC) and post-activity session (96 ± 66 HC, 160 ± 57 LC). There were no differences (p ≥ 0.16) in Appetite rating between the conditions at the pre-meal and four hours post-meal time points (p’s ≥ 0.16). Therefore, while Appetite was greater immediately after eating the LC meal than the HC meal, that difference is eliminated by four hours post-meal which is likely to be the time the next meal is consumed.Journal of Nutritional Health & Food Engineering. 07/2014; 1(4):20.
- International journal of obesity (2005) 09/2013; · 5.22 Impact Factor
High-intensity intermittent exercise attenuates ad-libitum
AY Sim1, KE Wallman1, TJ Fairchild2and KJ Guelfi1
OBJECTIVE: To examine the acute effects of high-intensity intermittent exercise (HIIE) on energy intake, perceptions of appetite
and appetite-related hormones in sedentary, overweight men.
DESIGN: Seventeen overweight men (body mass index: 27.7±1.6kgm?2; body mass: 89.8±10.1kg; body fat: 30.0±4.3%;
VO2peak: 39.2±4.8mlkg?1min?1) completed four 30-min experimental conditions using a randomised counterbalanced design.
CON: resting control, MC: continuous moderate-intensity exercise (60% VO2peak), HI: high-intensity intermittent exercise (alternating
60s at 100% VO2peakand 240s at 50% VO2peak), VHI: very-high-intensity intermittent exercise (alternating 15s at 170% VO2peakand
60s at 32% VO2peak). Participants consumed a standard caloric meal following exercise/CON and an ad-libitum meal 70min later.
Capillary blood was sampled and perceived appetite assessed at regular time intervals throughout the session. Free-living energy
intake and physical activity levels for the experimental day and the day after were also assessed.
RESULTS: Ad-libitum energy intake was lower after HI and VHI compared with CON (P¼0.038 and P¼0.004, respectively), and VHI
was also lower than MC (P¼0.028). Free-living energy intake in the subsequent 38h remained less after VHI compared with CON
and MC (Pp0.050). These observations were associated with lower active ghrelin (Pp0.050), higher blood lactate (Pp0.014) and
higher blood glucose (Pp0.020) after VHI compared with all other trials. Despite higher heart rate and ratings of perceived exertion
(RPE) during HI and VHI compared with MC (Pp0.004), ratings of physical activity enjoyment were similar between all the exercise
trials (P¼0.593). No differences were found in perceived appetite between trials.
CONCLUSIONS: High-intensity intermittent exercise suppresses subsequent ad-libitum energy intake in overweight inactive men.
This format of exercise was found to be well tolerated in an overweight population.
International Journal of Obesity advance online publication, 9 July 2013; doi:10.1038/ijo.2013.102
Keywords: food intake; appetite; interval; ghrelin; overweight
Exercise has a prominent role in improving the comorbidities of
obesity,1as well as contributing to a negative energy balance by
increasing energy expenditure.2,3Importantly, exercise has also
been shown to assist in weight management by directly
influencing the total amount of energy consumed, the circulating
concentration of a number of appetite-related hormones and
feelings of hunger and satiety.4–6In particular, manipulation of
the intensity and type of exercise employed may alter appetite-
related measures. In support of this view, a recent study reported
reduced ad-libitum energy intake at a lunch and dinner meal
following a bout of stationary cycling performed at high-intensity
(75% VO2max) compared with an equicaloric bout of low-intensity
exercise (40% VO2max) in obese adolescents.7There is also
evidence to suggest that the intensity of exercise may influence
the circulating levels of appetite-related hormones. Erdmann et al.8
reported that cycling at 100W was associated with lower ghrelin
(hunger-stimulating hormone) compared with cycling at 50W.
Likewise, Ueda et al.9showed a greater rise in the satiety hormone
peptide tyrosine–tyrosine (PYY) in response to high (75% VO2max)
compared with moderate-intensity (50% VO2max) exercise.
Prolonged and continuous high-intensity exercise may, how-
ever, not be sustainable in a sedentary overweight population.
An alternative may be the use of high-intensity intermittent
exercise (HIIE) that involves the performance of short bouts
exercise at lower intensities. This form of exercise has recently
gained increasing popularity, given the significant improvements
implementation of HIIE, we have recently shown that HIIE,
consisting of maximal 4-s sprints repeated every minute with
moderate-intensity exercise between sprints, suppressed post-
exercise energy intake in overweight boys compared with a
addition, participants reported that they preferred to participate
in HIIE over the continuous moderate-intensity exercise, despite
the fact that the HIIE involved a greater total amount of work.6
However, the role of the gastrointestinal hormones in regulating
appetite following HIIE has not previously been examined, and
whether similar suppression of appetite would be observed in
overweight adults while performing a matched amount of total
work is not known. Therefore, the aim of this study was to
investigate the acute effects of HIIE compared with continuous
moderate-intensity exercise of equicaloric cost on subsequent
energy intake, appetite-related hormones and perceptions of
appetite in a group of sedentary, overweight men.
1School of Sport Science, Exercise and Health, The University of Western Australia, Perth, Western Australia, Australia and2School of Psychology and Exercise Science, Murdoch
University, Perth, Western Australia, Australia. Correspondence: AY Sim, School of Sport Science, Exercise and Health, The University of Western Australia, 35 Stirling Highway,
Perth, WA 6009, Australia.
Received 12 February 2013; revised 16 April 2013; accepted 20 May 2013; accepted article preview online 4 June 2013
International Journal of Obesity (2013), 1–6
& 2013 Macmillan Publishers LimitedAll rights reserved 0307-0565/13
MATERIALS AND METHODS
Seventeen overweight, inactive men (age: 30±8 years; body mass index:
27.7±1.6kgm?2; body mass: 89.8±10.1kg; body fat: 30.0±4.3%; VO2peak:
39.2±4.8mlkg?1min?1; resting metabolic rate: 8021±843kJ) volun-
teered from the community through advertisement (flyers, posters, social
media and e-mail). Inclusion criteria were a body mass index of
25.0–29.9kgm?2and physical inactivity; defined as performing two or
less 30-min exercise sessions of moderate to vigorous intensity per week.11
Exclusion criteria were a history of medical conditions and/or eating
disorders known to affect appetite, or a score X3.5 on the restraint scale of
the Dutch Eating Behaviour Questionnaire.12Written consent was given by
all participants, and the study was approved by the Human Research Ethics
Committee at the University of Western Australia (UWA).
Participants attended the laboratory for an initial familiarisation session
and collection of baseline data. Participants then completed four
experimental trials using a randomised counterbalanced design. The
experimental trials comprised 30min of (i) MC: continuous exercise
performed at moderate intensity (60% VO2peak), (ii) HI: intermittent exercise
consisting of alternating high and lower intensity efforts performed at a
ratio of 1:4 (60s at 100% VO2peak: 240s at 50% VO2peak), (iii) VHI:
intermittent exercise consisting of alternating very-high and lower
intensity efforts performed at a ratio of 1:4 (15s at 170% VO2peak: 60s at
32% VO2peak) and (iv) CON: control trial involving supine rest. The total
mechanical work performed across each exercise protocol was matched.
Experimental trials were performed at the same time of day and on the
same day of the week, with a minimum of 1 week between visits. Primary
outcome measures included post-exercise ad-libitum energy intake,
changes in plasma concentrations of appetite-related hormones following
a standard caloric load and ratings of perceived appetite.
Baseline testing and familiarisation
The initial laboratory session included measurement of height and body
composition using a GE Lunar Prodigy Vision Dual-energy X-ray
absorptiometry machine (GE Medical Systems, Madison, WI, USA). Each
participant’s peak aerobic capacity (VO2peak) was assessed using a
continuous incremental cycling test performed on a calibrated front
access air-braked cycle ergometer (Model EX-10, Repco Cycle, Huntingdale,
Victoria, Australia) that was interfaced with a customised software program
(Cyclemax, School of Sport Science, Exercise and Health, UWA, Perth,
Western Australia, Australia), which provided a continuous record and
visual display of cycling power output. This test involved a starting
workload of 50W that increased by 30W every 3min until volitional
exhaustion. Throughout this test, each participant wore a heart rate (HR)
monitor and breathed through a mouthpiece that was connected to a
calibrated computerised gas analysis system (previously described by West
experimental protocols including a series of questionnaires to be
administered during each trial and blood sampling. Using data from the
VO2peaktest, each participant’s VO2–power relationship was determined to
calculate the cycling power output required to elicit the appropriate
exercise intensity for the experimental trials. It should be noted that work
intensities (that is, 170% VO2peak) were set based on a percentage of the
power output at VO2peak. Participants then completed 2min of each
exercise protocol. Finally, to minimise the novelty of having a meal in a
laboratory environment, participants were presented with a familiarisation
breakfast test meal. To ensure that there was no hedonic bias related to
the test meal, a standard nine-point hedonic scale was completed after its
consumption (hedonic rating: 7±1).14
In the 24h leading up to each experimental trial, participants were
required to refrain from vigorous physical activity and to document all
food and drink consumption. The dietary information was reviewed by the
investigator upon arrival to the laboratory, and participants were
instructed to replicate their food and drink intake prior to each subsequent
trial. A reminder was given prior to each trial and compliance was
confirmed by inspection of the records upon arrival to the laboratory.
On the morning of each trial, participants arrived at 0700 hours, having
fasted for 10h (apart from consuming 250ml of water between waking up
and arriving at the laboratory). Participants then either performed the
resting control protocol (CON) or one of the exercise protocols (MC, HI,
VHI). The exercise intensities were confirmed by monitoring cycling power
output and total work. HR was measured and participants’ ratings of
perceived exertion (RPE) were measured periodically using the Borg
scale.15On completion of each trial, enjoyment of physical activity was
assessed by using the Physical Activity Enjoyment Scale.16
Five minutes following exercise or CON, each participant was provided
with a standardised liquid meal (350ml, 1120kJ; 61% carbohydrates, 15%
protein and 30% fat; Up & Go liquid breakfast, Sanitarium, Berkeley Vale,
NSW, Australia) to consume in a 2-min period to allow for subsequent
comparison of the postprandial responses of appetite-related blood
variables and perceived appetite between trials. During this time (60min
postprandial), participants sat quietly either reading or using a computer.
Then, 70min after consumption of the liquid meal, participants were
provided with a second meal for a fixed duration of 20min. During this
period, participants were instructed to eat ad-libitum until a self-regulated
satisfactory level of satiety was reached (that is, ‘eat till comfortably full’). This
meal consisted of porridge made from a standardised mixture of instant oats
(Oats Quick Sachet—Creamy Honey, Uncle Tobys, Nestle Australia, Sydney,
NSW, Australia) and milk (HiLo Milk, Pura, Melbourne, VIC, Australia). A
standardised bottle of plain drinking water (B1000ml) was also made
available during this time. The breakfast porridge and drinking water were
weighed before and re-weighed after consumption. To minimise the
influence of environmental factors on eating behaviour,17(i) participants
always consumed from the same bowl, (ii) investigator left the nutrition
laboratory during consumption, (iii) ambient temperature was controlled
(21–231C), (iv) amount of porridge provided was the same in each trial and
(v) more than a sufficient amount was provided (that is, eight serves of oats
and milk mixture). This laboratory meal has been previously reported to
have a test–retest correlation of 0.91.13
Assessment of perceptions of appetite
Perceptions of appetite were assessed using a modified visual analogue
scale18at (i) baseline, (ii) immediately post exercise/CON, (iii) 30min post
standard meal, (iv) 60min post standard meal and (v) post ad-libitum meal.
The visual analogue scale took the form of five straight lines (100mm),
each accompanied by a question anchored with words representing
opposing extreme states of fullness, hunger, satiation, desire to eat and
prospective food consumption at either end.
Assessment of appetite-related blood variables
To determine the endocrinal and metabolic factors reported to be involved
in the regulation of energy intake, capillary blood was sampled at: (i) baseline,
(ii) immediately post exercise/CON, (iii) 30min post standard meal and (iv)
60min post standard meal. Blood (500ml) was collected from a fingertip
using a sterile lancet (Unistick 2 Normal; Owen Mumford, Oxford, UK) after
warming the entire hand in a box heated with warm air (B601C). Blood
glucose and lactate concentrations were measured using a blood gas
analyzer (35ml; Radiometer, Copenhagen, Denmark). The remaining blood
was treated with EDTA (Microtainer tubes with K2E (K2EDTA), BD Microtainer,
Franklin Lakes, NJ, USA) and serine protease inhibitor (20ml per 500ml of
blood; Pefabloc SC, Roche Diagnostics, Sydney, New South Wales, Australia)
before being centrifuged at 1020g for 10min. Plasma obtained was stored at
B?801C and later analysed for a range of appetite-related hormones: PYY,
pancreatic polypeptide (PP), active ghrelin, leptin and insulin; using a
commercially available assay kit (Milliplex Human Gut Hormone Panel;
Millipore Corporation, Billerica, MA, USA).
Assessment of free-living energy intake and physical activity levels
Energy intake and physical activity levels were assessed for the remainder
of the experimental day, as well as the next day using a self-recorded food
diary and accelerometry (ActiGraph, Pensacola, FL, USA), respectively.
Instructions on the use (including a 1-day example), and the necessity for
accurate and detailed recordings of energy intake immediately after
consumption were emphasised. Portable weighing scales were provided to
assist recording. The total kilojoules ingested were calculated using
commercially available software (Foodworks; Xyris Software, Kenmore Hills,
QLD, Australia). The estimated energy expenditure through physical
activity was determined using ActiLife software (ActiGraph).
One-way analysis of variance with repeated measures was used to assess
the effect of trial on ad-libitum energy intake and physical activity
enjoyment. Changes in blood variables, free-living energy intake and
HIIE attenuates energy intake
AY Sim et al
International Journal of Obesity (2013) 1–6
& 2013 Macmillan Publishers Limited
physical activity, and perceptions of appetite were compared using two-
way (trial x time) repeated measures analysis of variance. Post hoc pairwise
comparisons using Bonferroni adjustments were used to determine where
any differences lay. Statistical significance was accepted at Pp0.05 (SPSS
version 20, IBM Corporation, Armonk, NY, USA).
Energy intake and expenditure from physical activity 24h prior to
each experimental session were well-matched (energy intake:
9609±3488kJ; P¼0.852; energy expenditure: CON 1917±930,
MC 1885±888, HI 1870±958, VHI 1907±995kJ; P¼0.914).
Likewise, there were no differences in environmental character-
istics between trials (temperature: CON 21.1±0.6, MC 21.1±0.4,
HI 20.9±0.6, VHI 21.1±0.41C; P¼0.624; humidity: CON 49±10,
MC 47±8, HI 42.4±9, VHI 47±7%; P¼0.146) or the total
mechanical work performed (PX0.05; Table 1). There was a main
effect of trial for both HR and RPE (Po0.001), with a higher HR and
RPE during the exercise trials compared with CON (Po0.001;
Table 1). However, the increase was greater with HI and VHI
compared with MC (Pp0.004), and RPE was greater in VHI
compared with HI (P¼0.028). Physical activity enjoyment was
similar between the exercise trials (MC 85±13, HI 86±11, VHI
Post-exercise ad-libitum energy intake
There was a main effect of trial on ad-libitum energy intake
(Po0.001; Table 2). Post hoc analysis revealed that energy intake
was lower following HI and VHI compared with CON (P¼0.038
and P¼0.004, respectively). Ad-libitum energy intake after VHI was
also found to be lower compared with MC (P¼0.028). Of note,
there was a main effect of trial on water intake at the ad-libitum
(327±164ml) compared with CON (195±121ml) (P¼0.001).
Descriptive characteristics of 30min of rest (CON), MC, HI and
CONMC HI VHI
Average heart ratea
Abbreviations: HI, high-intensity intermittent exercise; MC, moderate
intensity continuous exercise; RPE, rating of perceived exertion; VHI,
very-high-intensity intermittent exercise. Values presented as mean±s.d.;
cSignificantly greater than MC.dSignificantly greater than HI (Pp0.05).
aMain effect of trial, Pp0.05.
bSignificantly greater than CON.
HI or VHI
Ad-libitum energy intake following 30min of rest (CON), MC,
Abbreviations: HI, high-intensity intermittent exercise; MC, moderate
intensity continuous exercise; VHI, very-high-intensity intermittent exer-
cise. Values presented as mean±s.d.; (n¼17).aMain effect of trial, Pp0.05.
bSignificantly different from CON.
cSignificantly different from MC
VAS - Hunger (mm)
VAS - Fullness (mm)
VAS - Satiation (mm)
VAS - Desire To Eat (mm)
VAS - Prospective Food
perceived satiation (c), perceived desire to eat (d) and prospective
food consumption (e) following 30min of VHI, HI, MC or rest (CON)
(n¼17). The downward arrow (k) and upward arrow (m) indicate the
timing of the standard liquid meal and ad-libitum meal, respectively.
#Significantly different from baseline (Pp0.05).
Mean (±s.e.) perceived hunger (a), perceived fullness (b),
HIIE attenuates energy intake
AY Sim et al
& 2013 Macmillan Publishers Limited International Journal of Obesity (2013) 1–6
Perception of appetite
There was no interaction of trial and time on ratings of perceived
hunger (P¼0.630), fullness (P¼0.102), satiation (P¼0.520), desire
to eat (P¼0.337) and prospective food consumption (P¼0.157).
However, there was a main effect of time for each of these
variables (Po0.001; Figure 1), with increased fullness and satiation
along with decreased hunger, desire to eat and prospective food
consumption following the ad-libitum test meal.
Appetite-related blood variables
An interaction of trial and time on blood lactate (Po0.001)
revealed higher levels after VHI, followed by HI, MC and CON
(Pp0.014; Figure 2a). Blood lactate remained higher in VHI
compared with the other trials (Pp0.014) following 35min of
recovery, and remained higher than CON up to 65min post
exercise (P¼0.046). Likewise, there was an interaction effect of
trial and time on blood glucose concentrations (P¼0.004). Blood
glucose was higher after VHI exercise compared with CON, MC
and HI (Pp0.015; Figure 2b). There was also a significant main
effect of time (Po0.001), with increased blood glucose in
response to meal consumption.
There was an interaction effect of trial and time on the circulating
levels of active ghrelin (P¼0.001), with lower active ghrelin levels
immediately post VHI compared with CON, MC and HI (Pp0.050;
Figure 2c). There was also a main effect of time on active ghrelin
(P¼0.001), with a lower level at 35min (P¼0.007) and 65min post
exercise (P¼0.007) compared with the baseline. In contrast, there
was no interaction of trial and time on leptin (P¼0.400), PP
(P¼0.281), insulin (P¼0.705) or PYY (P¼0.148). However, there was
a main effect of time for each of these variables with increased PP
(Pp0.004), insulin (Pp0.003) and PYY (Pp0.037) in response to
caloric consumption, whereas leptin decreased over time (Pp0.007).
Free-living energy intake and physical activity
A main effect of trial (Po0.001) revealed lower daily energy intake
(includes both standard and ad-libitum test meal) after VHI
Blood Lactate (mmol/L)
Blood Glucose (mmol/L)
Active Ghrelin (pg/ml)
ghrelin (c), PP (d), leptin (e), insulin (f) and PYY (g) to 30min of rest
(CON), MC, HI or VHI. The downward arrow (k) indicates the timing
of the standard liquid meal.
bSignificantly different from MC.
#Significantly different from baseline. (Pp0.05).
Mean (±s.e.) response of lactate (a), glucose (b), active
aSignificantly different from CON.
cSignificantly different from HI.
Daily Energy Intake (kJ)
Day of trial Day after trial
Daily Physical Activity (kJ)
estimated free-living physical activity (b) over 2 days (day of trial and
day after trial) following 30min of rest (CON), MC, HI or VHI. (n¼17).
aSignificantly different from CON.bSignificantly different from MC.
#Significantly different between days (Pp0.05).
Mean (±s.e.) estimated free-living energy intake (a) and
HIIE attenuates energy intake
AY Sim et al
International Journal of Obesity (2013) 1–6
& 2013 Macmillan Publishers Limited
compared with CON and MC (P¼0.003 and P¼0.010, respec-
tively; Figure 3a). There was also a main effect of time (day)
(P¼0.014), with higher total energy intake on the day of the trial
compared with the day after the trial. In contrast, there was no
effect of trial or time on the estimated energy expenditure from
physical activity upon leaving the laboratory (P¼0.710; Figure 3b).
The present study investigated the acute effects of HIIE compared
with continuous moderate-intensity exercise or rest on subse-
quent energy intake in sedentary, overweight men. Total ad-
libitum energy intake after HI and VHI was lower compared with
CON, and energy intake following VHI was also lower than MC.
These observations were associated with lower active ghrelin and
higher blood glucose concentrations following VHI compared with
the other trials, and higher blood lactate concentrations after HI
and VHI compared with MC and CON. Importantly, the suppres-
sion of energy intake after VHI compared with CON and MC was
maintained for more than 24h.
This study is the first to demonstrate a suppression of energy
intake following an acute bout of exercise consisting of very-high-
intensity intermittent efforts (X100% VO2peak) in overweight men.
The experimental design of this study, in particular the use of
distinctively different exercise intensities during equicaloric
exercise trials (that is, MC, HI, VHI; 60, 100, 170% VO2peak,
respectively), allowed us to examine the impact exercise intensity
may have on post-exercise energy intake. Our results show that
there was a more pronounced suppression of energy intake as the
intensities employed increased (that is, VHI resulted in the greatest
suppression of energy intake) and suggest that exercise intensity
mediates subsequent energy intake, at least in the short term. To
the authors’ knowledge, only one other study has investigated the
effect of intermittent sprint efforts on energy intake and its
regulation. Deighton et al.19found no difference in energy intake
after a bout of HIIE consisting of six 30-s sprints over 30min
compared with 60min of endurance exercise and rest. However,
these exercise protocols were not matched for work; they
consisted of a lower volume of sprint efforts compared with the
present study and was performed in normal-weight individuals.
Surprisingly, we observed no difference in the perceived appetite
ratings between trials, despite suppression of ad-libitum energy
intake after HIIE. The reason for this is unclear, although previous
research has shown that feelings of appetite may not always
reflect actual food intake.20
A number of mechanisms may contribute to the lower energy
intake following HI and VHI. In the current study, circulating active
ghrelin was transiently lower following VHI compared with all
other trials. Notably, the reduction in the circulating concentration
of active ghrelin after VHI is consistent with the findings of
Deighton et al.,19who reported a suppression of active ghrelin
after 30min of sprint interval exercise. Given that active ghrelin
has been shown to exert an orexigenic influence on energy intake
and has a role in initiating feeding,21the lower active ghrelin may
partly explain the suppression of energy intake following VHI.
Diversion of blood flow away from the gastrointestinal tract has
been suggested to be the most likely cause of circulating active
ghrelin suppression in response to exercise.22Of relevance, it has
been reported that gastrointestinal blood flow may be reduced by
up to about 80% during maximal-intensity exercise.23Although
the plasma concentration of insulin and leptin were not different
between conditions, it has been established that sensitivity to
these hormones is increased post exercise.24,25Whether sensitivity
to these appetite-related hormones is influenced by exercise
intensity is yet to be determined. Further, although changes in PP
and PYY in response to exercise have been reported,26,27no
changes were detected between conditions in the present study.
Possible reasons for this lack of response were the shorter
duration of exercise performed (30min in the present study
compared with 60min26,27) and that blood in the present study
was sampled before and after, but not during exercise.26It should
be noted that PP and PYY, although not significant, were highest
following the VHI trial.
Another possible mechanism that may explain the effect of HIIE
on energy intake is the circulating concentration of the two key
metabolites, lactate and glucose. The HIIE trials adopted in the
current study resulted in higher post-exercise blood lactate
compared with MC and CON, which persisted 1h post VHI
compared with CON. Given that elevated blood lactate has been
reported to suppress energy intake,28,29the comparatively higher
levels of blood lactate during the HIIE sessions may, to some
extent, have contributed to the suppressed ad-libitum energy
intake. Blood glucose levels post exercise were also higher after
VHI compared with CON, MC and HI. Specifically, an increase in
circulating blood glucose levels has been shown to reduce short-
term food intake.30,31
Although acute changes in food intake are of interest, the
persistence of these changes beyond the post-exercise meal is
relevant to better understand how exercise affects free-living
energy intake. Whereas no differences in daily physical activity
were noted upon leaving the laboratory, differences were
observed in daily energy intake between trials, with total energy
intake over the subsequent 2 days after the VHI trial lower
compared with CON and MC. This finding corroborates the
observations of Thivel et al.,7who reported that a single bout of
high-intensity exercise suppressed spontaneous energy intake in
the subsequent 24h compared with either a single bout of lower-
intensity exercise or rest in obese adolescents.
Finally, as enjoyment of physical activity has been reported to be
a key factor in physical activity performance and exercise
adherence,32,33the present study aimed to assess enjoyment of
the different exercise trials. Whereas others have reported HIIE to
be more enjoyable than moderate-intensity continuous exercise,34
the present study found similar enjoyment between trials. Impor-
tantly, enjoyment was not compromised in HI and VHI, despite
higher mean RPE and HR during exercise compared with MC.
In summary, the key findings of this study are that (i) HIIE
suppresses subsequent ad-libitum energy intake in overweight,
inactive men compared with the rest; and (ii) HIIE is well tolerated
in a sedentary and overweight population. The suppression of ad-
libitum energy intake is greater with higher-intensity intermittent
exercise and is likely attributable to increased levels of circulating
blood lactate and blood glucose, together with a lower
concentration of active ghrelin following the high-intensity
exercise bouts. Whether these observations are maintained under
chronic conditions (that is, training) and apply to women will need
to be determined in future research. The findings of this study
highlight the importance of appropriate exercise prescription,
given the evidence both in this study and that of others that
exercise intensity may alter important clinical measures. As such,
findings of this study have implications for exercise guidelines and
prescription for weight management, and are an important
consideration for both the overweight individual living with major
health risks, as well as for our community dealing with the burden
of the current obesity pandemic.
CONFLICT OF INTEREST
The authors declare no conflict of interest.
The hormone assays were carried out with the facilities at the Centre for Microscopy,
Characterisation and Analysis, The University of Western Australia that are supported
by the fundings of the University, State and Federal Government. TJF is in receipt of a
McCusker Charitable Foundation grant, which was used to help defray costs of the
HIIE attenuates energy intake
AY Sim et al
& 2013 Macmillan Publishers LimitedInternational Journal of Obesity (2013) 1–6
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International Journal of Obesity (2013) 1–6
& 2013 Macmillan Publishers Limited