Acute energy compensation and macronutrient intake following exercise in active and inactive males who are normal weight

Compensatory effects of different exercise durations on non-exercise physical activity, appetite, and energy intake in normal weight and overweight adults

Objectives: To examine compensatory changes of different exercise durations on non-exercise physical activity (NEPA), appetite, and energy intake (EI) in normal and overweight adults, and to determine if different body mass index of individuals interact with these compensatory effects.

Methods: Ten normal weight adults (nine females and one male; age: 24.0 ± 0.4 years; BMI: 20.7 ± 0.5 kg/m²) and ten overweight adults (six females and four males; age: 24.5 ± 0.9 years; BMI: 25.9 ± 0.4 kg/m²) participated in this study. The participants completed two exercise trials: short-duration continuous training (SDCT) and long-duration continuous training (LDCT), i.e., a 40 min short-duration and an 80 min long-duration continuous training in a randomized order. Total physical activity and NEPA were monitored using an accelerometer for seven consecutive days, which involved a two-day baseline observation period (C-pre-Ex), three-day exercise intervention period (Ex), and two-day follow-up period (C-post-Ex). Blood samples were collected for appetite-related hormone analysis. Appetite score was assessed using the visual analogue scale. Energy intake was evaluated by weighing the food and recording diaries.

Results: The NEPA evaluation showed that it was higher for SDCT than for LDCT in the C-post-Ex period (F (1, 19) = 8.508, p = 0.009) in the total sample. Moreover, results also indicated that NEPA was lower for LDCT (F (2, 18) = 6.316, p = 0.020) and higher for SDCT (F (2, 18) = 3.889, p = 0.026) in the C-post-Ex period than in the C-pre-Ex and Ex periods in overweight group. Acyl-ghrelin revealed a main effect of time in the total sample and in normal weight and overweight groups; it was lower in the C-post-Ex period than in the C-pre-Ex and Ex periods (all p < 0.05). Total EI analysis revealed no significant changes in either the total sample or in the normal weight and overweight groups.

Conclusion: These findings demonstrate that short duration exercise led to a compensatory increment in NEPA, whereas long duration exercise induced a compensatory decrease in NEPA. Moreover, there was a higher and delayed compensatory response in overweight adults than in normal weight adults. Nevertheless, energy intake was not changed across time, regardless of exercise duration.

Examining Anxiety, Sleep Quality, and Physical Activity as Predictors of Depression among University Students from Saudi Arabia during the Second Wave of the COVID-19 Pandemic

Conducted during the second wave of the pandemic, this cross-sectional study examined the link between sleep quality, physical activity, exposure, and the impact of COVID-19 as predictors of mental health in Saudi undergraduate students. A convenience sample of 207 participants were recruited, 89% of whom were females and 94% were single. The measures included questionnaires on the level of exposure and the perceived impact of COVID-19, a physical activity measure, GAD-7, PHQ-9, and PSQI. The results indicated that approximately 43% of participants exhibited moderate anxiety, and 50% were at risk of depression. Overall, 63.93% of students exposed to strict quarantine for at least 14 days (n = 39) exhibited a high risk of developing depression (χ2(1) = 6.49, p < 0.05, ϕ = 0.18). A higher risk of depression was also found in students whose loved ones lost their jobs (χ2(1) = 4.24, p < 0.05, ϕ = 0.14). Moreover, there was also a strong association between depression and anxiety (β = 0.33, p < 0.01), sleep quality (β = 0.32, p < 0.01), and the perceived negative impact of COVID-19 on socio-economic status (β = 0.26, p < 0.05), explaining 66.67% of depression variance. Our study highlights the socio-economic impact of this pandemic and the overwhelming prevalence of depression.

Post-exercise energy intake: do the intensity and mode of exercise matter? A systematic review and meta-analysis comparing high-intensity interval with moderate-intensity continuous protocols

The present systematic review and meta-analysis aimed to compare the impact of exercise intensity and mode (high-intensity interval exercise-HIIE or sprint interval exercise-SIE versus moderate-intensity continuous exercise-MICE) on post-exercise ad libitum energy intake. The studies were required to have at least two exercise conditions (HIIE or SIE vs MICE). Overall, 642 manuscripts were initially identified and 17 met the eligibility criteria. The random effect meta-analysis did not reveal differences for absolute energy intake (28 pairwise comparisons) between HIIE (p = 0.54; 95% Confidence Interval - CI: -0.14 to 0.26; 22 pairwise comparisons) or SIE (p = 0.08; 95% CI -0.65 to 0.03; 6 pairwise comparisons) versus MICE, neither for relative energy intake (p = 0.97; 95% CI: -0.35 to 0.10 for HIIE; p = 0.28; 95% CI: -1.03 to 0.06 for SIE) with five and one pairwise comparisons, respectively. Subgroup analyses for methods to evaluate ad libitum energy intake, body mass, sex, volume, and timing of exercise were non-significant. Inspecting each study, two pairwise comparisons reported lower post-exercise absolute energy intake in HIIE compared to control (CRTL), and three pairwise comparisons reported lower absolute energy intake after SIE compared to MICE. None pairwise comparison reported differences between protocols (HIIE or SIE versus MICE) for relative energy intake. In conclusion, the meta-analysis did not show differences between protocols for absolute and relative energy intake; five pairwise comparisons from 28 demonstrated lower absolute energy intake in HIIE or SIE compared to CRTL or MICE. Further studies are needed to address the key relevant variables in which exercise intensity and mode may impact energy intake.

Planned morning aerobic exercise in a fasted state increases energy intake in the preceding 24 h

Purpose

We previously observed increased energy intake (EI) at the meal before planned afternoon exercise, but the proximity of the meal to exercise might have reduced the scale of the pre-exercise anticipatory eating. Therefore, this study examined EI in the 24 h before fasted morning exercise.

Methods

Fourteen males, experienced with gym-based aerobic exercise (age 25 ± 5 years, BMI 23.8 ± 2.5 kg/m²), completed counterbalanced exercise (EX) and resting (REST) trials. On day 1, subjects were told the following morning’s activity (EX/REST), before eating ad-libitum laboratory-based breakfast and lunch meals and a home-based afternoon/evening food pack. The following morning, subjects completed 30-min cycling and 30-min running (EX; 3274 ± 278 kJ) or 60-min supine rest (REST; 311 ± 34 kJ) fasted. Appetite was measured periodically, and EI quantified.

Results

Afternoon/evening EI (EX 7371 ± 2176 kJ; REST 6437 ± 2070 kJ; P = 0.017) and total 24-h EI (EX 14,055 ± 3672 kJ; REST 12,718 ± 3379 kJ; P = 0.011) were greater during EX, with no difference between trials at breakfast (P = 0.761) or lunch (P = 0.071). Relative EI (EI minus energy expended through EX/REST) was lower in EX (EX 10,781 ± 3539 kJ; REST 12,407 ± 3385 kJ; P = 0.004).

Conclusion

This study suggests planned fasted aerobic exercise increases EI during the preceding afternoon/evening, precipitating a ~ 10% increase in EI in the preceding 24-h. However, this increase did not fully compensate for energy expended during exercise; meaning exercise induced an acute negative energy balance.

Influence of postexercise fasting on hunger and satiety in adults

Research demonstrates that exercise acutely reduces appetite by stimulating the secretion of gut-derived satiety hormones. Currently there is a paucity of research examining the impact of postexercise nutrient intake on appetite regulation. The objective of this study was to examine how postexercise fasting versus feeding impacts the postexercise appetite response. In a randomized crossover intervention, 14 participants (body mass index: 26.9 ± 3.5 kg·m^-2; age: 26.8 ± 6.7 years) received 1 of 2 recovery beverages: (i) water control (FAST) or (ii) sweetened-milk (FED) after completing a 45-min (65%-70% peak oxygen uptake) evening exercise session (∼1900 h). Energy intake was assessed through a fasted ad libitum breakfast meal and 3-day food diaries. Perceived appetite was assessed using visual analogue scales. Appetite-regulating hormones glucagon-like peptide-1 (GLP-1), peptide tyrosine-tyrosine (PYY), and acyl-ghrelin were assessed pre-exercise, 1 h after exercise, and the morning following exercise. FAST increased subjective hunger compared with FED (P < 0.05). PYY and GLP-1 after exercise were decreased and acyl-ghrelin was increased in FAST, with these differences disappearing the day after exercise (P < 0.05). Ad libitum energy intake at breakfast the following morning did not differ between trials. Overall, in the absence of postexercise macronutrient consumption, there was a pronounced increase in objective and subjective appetite after exercise. The orexigenic effects of postexercise fasting, however, were not observed the morning following exercise. Novelty Postexercise fasting leads to reduced GLP-1 and PYY and increased hunger. Reduced GLP-1 and PYY after exercise is blunted by postexercise nutrient intake. Energy intake the day after exercise is not influenced by postexercise fasting.

The Effects of the Type of Exercise and Physical Activity on Eating Behavior and Body Composition in Overweight and Obese Subjects

The aim of this study was to examine whether a type of exercise favors better compliance with a prescribed diet, higher eating-related motivation, healthier diet composition or greater changes in body composition in overweight and obese subjects. One hundred and sixty-two (males n = 79), aged 18-50 years, were randomized into four intervention groups during 24 weeks: strength, endurance, combined strength + endurance and guideline-based physical activity; all in combination with a 25-30% caloric restriction diet. A food frequency questionnaire and a "3-day food and drink record" were applied pre- and post-intervention. Diet and exercise-related motivation levels were evaluated with a questionnaire developed for this study. Body composition was assessed by DXA and habitual physical activity was measured by accelerometry. Body weight, body mass index (BMI) and body fat percentage decreased and lean body mass increased after the intervention, without differences by groups. No interactions were observed between intervention groups and time; all showing a decreased in energy intake (p < 0.001). Carbohydrate and protein intakes increased, and fat intake decreased from pre- to post-intervention without significant interactions with intervention groups, BMI category or gender (p < 0.001). Diet-related motivation showed a tendency to increase from pre- to post-intervention (70.0 ± 0.5 vs 71.0 ± 0.6, p = 0.053), without significant interactions with intervention groups, BMI or gender. Regarding motivation for exercise, gender x time interactions were observed (F(1,146) = 7.452, p = 0.007): Women increased their motivation after the intervention (pre: 17.6 ± 0.3, post: 18.2 ± 0.3), while men maintained it. These findings suggest that there are no substantial effects of exercise type on energy intake, macronutrient selection or body composition changes. After a six-month weight loss program, individuals did not reduce their motivation related to diet or exercise, especially women. Individuals who initiate a long-term exercise program do not increase their energy intake in a compensatory fashion, if diet advices are included.

Acute and Chronic Effects of Exercise on Appetite, Energy Intake, and Appetite-Related Hormones: The Modulating Effect of Adiposity, Sex, and Habitual Physical Activity

Exercise facilitates weight control, partly through effects on appetite regulation. Single bouts of exercise induce a short-term energy deficit without stimulating compensatory effects on appetite, whilst limited evidence suggests that exercise training may modify subjective and homeostatic mediators of appetite in directions associated with enhanced meal-induced satiety. However, a large variability in responses exists between individuals. This article reviews the evidence relating to how adiposity, sex, and habitual physical activity modulate exercise-induced appetite, energy intake, and appetite-related hormone responses. The balance of evidence suggests that adiposity and sex do not modify appetite or energy intake responses to acute or chronic exercise interventions, but individuals with higher habitual physical activity levels may better adjust energy intake in response to energy balance perturbations. The effect of these individual characteristics and behaviours on appetite-related hormone responses to exercise remains equivocal. These findings support the continued promotion of exercise as a strategy for inducing short-term energy deficits irrespective of adiposity and sex, as well as the ability of exercise to positively influence energy balance over the longer term. Future well-controlled studies are required to further ascertain the potential mediators of appetite responses to exercise.

An acute bout of cycling does not induce compensatory responses in pre-menopausal women not using hormonal contraceptives

There is a clear need to improve understanding of the effects of physical activity and exercise on appetite control. Therefore, the acute and short-term effects (three days) of a single bout of cycling on energy intake and energy expenditure were examined in women not using hormonal contraceptives. Sixteen active (n = 8) and inactive (n = 8) healthy pre-menopausal women completed a randomised crossover design study with two conditions (exercise and control). The exercise day involved cycling for 1 h (50% of maximum oxygen uptake) and resting for 2 h, whilst the control day comprised 3 h of rest. On each experimental day participants arrived at the laboratory fasted, consumed a standardised breakfast and an ad libitum pasta lunch. Food diaries and combined heart rate-accelerometer monitors were used to assess free-living food intake and energy expenditure, respectively, over the subsequent three days. There were no main effects or condition (exercise vs control) by group (active vs inactive) interaction for absolute energy intake (P > 0.05) at the ad libitum laboratory lunch meal, but there was a condition effect for relative energy intake (P = 0.004, η_p² = 0.46) that was lower in the exercise condition (1417 ± 926 kJ vs. 2120 ± 923 kJ). Furthermore, post-breakfast satiety was higher in the active than in the inactive group (P = 0.005, η_p² = 0.44). There were no main effects or interactions (P > 0.05) for mean daily energy intake, but both active and inactive groups consumed less energy from protein (14 ± 3% vs. 16 ± 4%, P = 0.016, η_p² = 0.37) and more from carbohydrate (53 ± 5% vs. 49 ± 7%, P = 0.031, η_p² = 0.31) following the exercise condition. This study suggests that an acute bout of cycling does not induce compensatory responses in active and inactive women not using hormonal contraceptives, while the stronger satiety response to the standardised breakfast meal in active individuals adds to the growing literature that physical activity helps improve the sensitivity of short-term appetite control.

Does Habitual Physical Activity Increase the Sensitivity of the Appetite Control System? A Systematic Review

Background

It has been proposed that habitual physical activity improves appetite control; however, the evidence has never been systematically reviewed.

Objective

To examine whether appetite control (e.g. subjective appetite, appetite-related peptides, food intake) differs according to levels of physical activity.

Data Sources

Medline, Embase and SPORTDiscus were searched for articles published between 1996 and 2015, using keywords pertaining to physical activity, appetite, food intake and appetite-related peptides.

Study Selection

Articles were included if they involved healthy non-smoking adults (aged 18–64 years) participating in cross-sectional studies examining appetite control in active and inactive individuals; or before and after exercise training in previously inactive individuals.

Study Appraisal and Synthesis

Of 77 full-text articles assessed, 28 studies (14 cross-sectional; 14 exercise training) met the inclusion criteria.

Results

Appetite sensations and absolute energy intake did not differ consistently across studies. Active individuals had a greater ability to compensate for high-energy preloads through reductions in energy intake, in comparison with inactive controls. When physical activity level was graded across cross-sectional studies (low, medium, high, very high), a significant curvilinear effect on energy intake (z-scores) was observed.

Limitations

Methodological issues existed concerning the small number of studies, lack of objective quantification of food intake, and various definitions used to define active and inactive individuals.

Conclusion

Habitually active individuals showed improved compensation for the energy density of foods, but no consistent differences in appetite or absolute energy intake, in comparison with inactive individuals. This review supports a J-shaped relationship between physical activity level and energy intake. Further studies are required to confirm these findings.

PROSPERO Registration Number

CRD42015019696

Electronic supplementary material

The online version of this article (doi:10.1007/s40279-016-0518-9) contains supplementary material, which is available to authorized users.

The Effects of Food Labelling on Postexercise Energy Intake in Sedentary Women

Food labelling has been previously reported to influence energy intake (EI). Whether food labels influence postexercise EI remains to be determined. We assessed how food labelling and exercise (Ex) interact to influence food perception and postexercise EI. In this randomized crossover design, 14 inactive women participated in 4 experimental conditions: Ex (300 kcal at 70% of VO_2peak) and lunch labelled as low in fat (LF), Ex and lunch labelled as high in fat (HF), Rest and LF, and Rest and HF. The lunch was composed of a plate of pasta, yogurt, and oatmeal cookies, which had the same nutritional composition across the 4 experimental conditions. EI at lunch and for the 48-hour period covering the testing day and the following day was assessed. Furthermore, perceived healthiness of the meal and appetite ratings were evaluated. There were no effects of exercise and food labelling on EI. However, meals labelled as LF were perceived as heathier, and this label was associated with higher prospective food consumption. Initial beliefs about food items had a stronger effect on healthiness perception than the different food labels and explain the positive correlation with the amount of food consumed (ρ = 0.34, P < 0.001).

The Effect of a 20 km Run on Appetite Regulation in Long Distance Runners

The purpose of the present study was to investigate appetite-related hormonal responses and energy intake after a 20 km run in trained long distance runners. Twenty-three male long-distance runners completed two trials: either an exercise trial consisting of a 20 km outdoor run (EX) or a control trial with an identical period of rest (CON). Blood samples were collected to determine plasma acylated ghrelin, peptide YY_3-36 (PYY_3-36) and other hormonal and metabolite concentrations. Energy intake during a buffet test meal was also measured 30 min after the exercise or rest periods. Although plasma acylated ghrelin concentrations were significantly decreased after the 20 km run (p < 0.05), plasma PYY_3-36 did not change significantly following exercise. Absolute energy intake during the buffet test meal in EX (1325 ± 55 kcal) was significantly lower than that in CON (1529 ± 55 kcal), and there was a relatively large degree of individual variability for exercise-induced changes in energy intake (−40.2% to 12.8%). However, exercise-induced changes in energy intake were not associated with plasma acylated ghrelin or PYY_3-36 responses. The results demonstrated that a 20 km run significantly decreased plasma acylated ghrelin concentrations and absolute energy intake among well-trained long distance runners.

Effect of heat exposure and exercise on food intake regulation: A randomized crossover study in young healthy men

OBJECTIVE

The effect of physical activity on food intake regulation may be moderated by environmental temperature. The aim of the study was to determine the single and combined effects of metabolic activity and temperature on energy intake and its hormonal regulation.

METHODS

A randomized crossover study was conducted in the laboratory. Ten healthy and physically active young Afro-Caribbean men participated in four experimental sessions (rest at 22°C and 31°C and cycling at 60% of their maximal oxygen uptake at 22°C and 31°C, all for 40 min). Each test period was followed by a 30-min recovery period and then an ad libitum meal. The main outcome measures were energy balance, subjective appetite, and plasma pancreatic polypeptide (PP), cholecystokinin (CCK) and ghrelin concentrations.

RESULTS

Relative energy intake was significantly decreased whereas plasma PP was increased in the exercise conditions (p=0.004 and p=0.002, respectively). Postprandial levels of CCK were elevated only in the rest conditions. Exposure to heat induced a decrease in plasma ghrelin (p=0.031).

CONCLUSIONS

Exercise induced a short-term energy deficit. However, modifications in the hormonal regulation of food intake in response to short-term heat or heat and exercise exposure seem to be minor and did not induce changes in energy intake. This trial was registered at clinicaltrials.gov as NCT02157233.

Reciprocal Compensation to Changes in Dietary Intake and Energy Expenditure within the Concept of Energy Balance

An imbalance between energy intake and energy expenditure is the primary etiology for excess weight gain. Increased energy expenditure via exercise and energy restriction via diet are commonly used approaches to induce weight loss. Such behavioral interventions, however, have generally resulted in a smaller than expected weight loss, which in part has been attributed to compensatory adaptations in other components contributing to energy balance. Current research points to a loose coupling between energy intake and energy expenditure on a daily basis, and evidence for long-term adaptations has been inconsistent. The lack of conclusive evidence on compensatory adaptations in response to alterations in energy balance can be attributed to differences in intervention type and study population. Physical activity (PA) levels may be reduced in response to aerobic exercise but not in response to resistance exercise. Furthermore, athletic and lean adults have been shown to increase their energy intake in response to exercise, whereas no such response was observed in obese adults. There is also evidence that caloric restriction is associated with a decline in PA. Generally, humans seem to be better equipped to defend against weight loss than avoid weight gain, but results also show a large individual variability. Therefore, individual differences rather than group means should be explored to identify specific characteristics of "compensators" and "noncompensators." This review emphasizes the need for more research with simultaneous measurements of all major components contributing to energy balance to enhance the understanding of the regulation of energy balance, which is crucial to address the current obesity epidemic.

Exercise-trained men and women: role of exercise and diet on appetite and energy intake

The regulation of appetite and energy intake is influenced by numerous hormonal and neural signals, including feedback from changes in diet and exercise. Exercise can suppress subjective appetite ratings, subsequent energy intake, and alter appetite-regulating hormones, including ghrelin, peptide YY, and glucagon-like peptide 1(GLP-1) for a period of time post-exercise. Discrepancies in the degree of appetite suppression with exercise may be dependent on subject characteristics (e.g., body fatness, fitness level, age or sex) and exercise duration, intensity, type and mode. Following an acute bout of exercise, exercise-trained males experience appetite suppression, while data in exercise-trained women are limited and equivocal. Diet can also impact appetite, with low-energy dense diets eliciting a greater sense of fullness at a lower energy intake. To date, little research has examined the combined interaction of exercise and diet on appetite and energy intake. This review focuses on exercise-trained men and women and examines the impact of exercise on hormonal regulation of appetite, post-exercise energy intake, and subjective and objective measurements of appetite. The impact that low-energy dense diets have on appetite and energy intake are also addressed. Finally, the combined effects of high-intensity exercise and low-energy dense diets are examined. This research is in exercise-trained women who are often concerned with weight and body image issues and consume low-energy dense foods to keep energy intakes low. Unfortunately, these low-energy intakes can have negative health consequences when combined with high-levels of exercise. More research is needed examining the combined effect of diet and exercise on appetite regulation in fit, exercise-trained individuals.

Creating an acute energy deficit without stimulating compensatory increases in appetite: is there an optimal exercise protocol?

Recent years have witnessed significant interest from both the scientific community and the media regarding the influence of exercise on subsequent appetite and energy intake responses. This review demonstrates a consensus among the majority of scientific investigations that an acute bout of land-based endurance exercise does not stimulate any compensatory increases in appetite and energy intake on the day of exercise. Alternatively, preliminary evidence suggests that low volume, supramaximal exercise may stimulate an increase in appetite perceptions during the subsequent hours. In accordance with the apparent insensitivity of energy intake to exercise in the short term, the daily energy balance response to exercise appears to be primarily determined by the energy cost of exercise. This finding supports the conclusions of recent training studies that the energy expenditure of exercise is the strongest predictor of fat loss during an exercise programme.

Does increased exercise or physical activity alter ad-libitum daily energy intake or macronutrient composition in healthy adults? A systematic review

BACKGROUND

The magnitude of the negative energy balance induced by exercise may be reduced due to compensatory increases in energy intake.

OBJECTIVE

TO ADDRESS THE QUESTION: Does increased exercise or physical activity alter ad-libitum daily energy intake or macronutrient composition in healthy adults?

DATA SOURCES

PubMed and Embase were searched (January 1990-January 2013) for studies that presented data on energy and/or macronutrient intake by level of exercise, physical activity or change in response to exercise. Ninety-nine articles (103 studies) were included.

STUDY ELIGIBILITY CRITERIA

Primary source articles published in English in peer-reviewed journals. Articles that presented data on energy and/or macronutrient intake by level of exercise or physical activity or changes in energy or macronutrient intake in response to acute exercise or exercise training in healthy (non-athlete) adults (mean age 18-64 years).

STUDY APPRAISAL AND SYNTHESIS METHODS

Articles were grouped by study design: cross-sectional, acute/short term, non-randomized, and randomized trials. Considerable heterogeneity existed within study groups for several important study parameters, therefore a meta-analysis was considered inappropriate. Results were synthesized and presented by study design.

RESULTS

No effect of physical activity, exercise or exercise training on energy intake was shown in 59% of cross-sectional studies (n = 17), 69% of acute (n = 40), 50% of short-term (n = 10), 92% of non-randomized (n = 12) and 75% of randomized trials (n = 24). Ninety-four percent of acute, 57% of short-term, 100% of non-randomized and 74% of randomized trials found no effect of exercise on macronutrient intake. Forty-six percent of cross-sectional trials found lower fat intake with increased physical activity.

LIMITATIONS

The literature is limited by the lack of adequately powered trials of sufficient duration, which have prescribed and measured exercise energy expenditure, or employed adequate assessment methods for energy and macronutrient intake.

CONCLUSIONS

We found no consistent evidence that increased physical activity or exercise effects energy or macronutrient intake.

Energy compensation after an aerobic exercise session in high-fat/low-fit and low-fat/high-fit young male subjects

There is general agreement that exercise-induced energy expenditure is not entirely compensated for at the next meal or over the following 24 h, but inter-individual variability is high. The role of ‘fatness and fitness’ in this variability has never been assessed. Therefore, eighteen non-obese male subjects aged 22·2 (sd2·0) years were selected and separated into a ‘high-fatness and low-fitness’ (Hfat/Lfit,n9) and a ‘low-fatness and high-fitness’ (Lfat/Hfit,n9) group, according to three criteria: maximal oxygen uptake; weekly hours of physical activity; fat mass index. At 1 h before lunch, they were subjected to 60 min of exercise on a cycle ergometer (70 % VO2max), or stayed at rest. Then, they self-reported food intake in diaries until the next breakfast. Intake at lunch was not different between conditions, but was higher after exercise than after rest over the 24 h, leading to a significant but partial mean level of compensation of 49·8 (sem16·5) and 37·8 (sem24·6) % for the Hfat/Lfit and Lfat/Hfit groups, respectively. Energy compensation at lunch and over the 24 h were strongly correlated (r0·76,P< 0·001). Both groups consumed more fat and protein after exercise than after rest over the 24 h, but the percentage of energy derived from fat increased only in the Hfat/Lfit group (2·1 (sem0·6) %,P= 0·026). Thus, the energy cost of an aerobic exercise session was partially compensated over the next 24 h independently of the ‘fatness and fitness’ status, but ‘high-fat and low-fit’ individuals compensated more specifically on fats.

The effects of sex, metabolic syndrome and exercise on postprandial lipemia

OBJECTIVE

Exercise has been suggested to have cardioprotective benefits due to a lowering of postprandial triglycerides (PPTG). We hypothesized that a morning exercise bout would significantly lower PPTG measured over a full day, in response to moderate fat meals (35% energy) in men more so than women, and in metabolic syndrome (MetS) relative to normal weight (NW) individuals.

MATERIALS/METHODS

Participants completed two randomized study days; one control and one exercise day (60 min of morning exercise, 60% VO(2peak)). Meals were consumed at breakfast, lunch and dinner with the energy expended during exercise replaced on the active day. The areas (AUC) and incremental areas (IAUC) under the curve were calculated for total triglycerides, total cholesterol and other metabolites.

RESULTS

Exercise did not significantly change the PPTG AUC & IAUC overall, or within, or between, each sex or group (NW and MetS). Exercise induced a 30% decrease in total cholesterol IAUC (p=0.003) in NW subjects. Overall, women had a lower IAUC for PPTG compared to men (p=0.037), with the greatest difference between MetS women and MetS men, due to a sustained drop in TG after lunch in the women. This suggests that PP, rather than fasting, lipid analyses may be particularly important when evaluating sex differences in metabolic risk.

CONCLUSIONS

With energy replacement, moderate morning exercise did not result in a significant decrease in PPTG excursions. Exercise did elicit a significant decrease in PP cholesterol levels in NW subjects, suggesting a potential mechanism for the cardioprotective effects of exercise.

Effects of exercise before or after meal ingestion on fat balance and postprandial metabolism in overweight men

It is unclear how timing of exercise relative to meal ingestion influences substrate balance and metabolic responses. The present study aimed to compare the effects of exercise performed before or after breakfast on fat balance and postprandial metabolism. A total of ten sedentary overweight men (aged 28·1 (sem 10·7) years, BMI 29·0 (sem 2·8) kg/m2) underwent three trials in random order involving: (1) performing no exercise (CON), or walking for 60 min at 50 % maximal O2 uptake either (2) before (Ex-Meal) or (3) after (Meal-Ex) consuming a standardised breakfast meal. In each trial an ad libitum lunch was provided 3·5 h after breakfast. Substrate utilisation was assessed by indirect calorimetry and blood was taken at regular intervals over an 8·5 h observation period. At the end of the observation period, fat balances in the Ex-Meal ( − 1043 (sem 270) kJ) and Meal-Ex ( − 697 (sem 201) kJ) trials were both significantly lower than CON (204 (sem 165) kJ) and fat balance in the Ex-Meal trial was significantly lower than in the Meal-Ex trial (all P <0·0001). Compared with the CON trial, the 8·5 h postprandial TAG response was only significantly lowered in the Ex-Meal trial ( − 17 %, P =0·025) and not in the Meal-Ex trial ( − 11 %, P =0·20). Both the Ex-Meal and Meal-Ex trials showed significantly lowered insulin responses relative to the CON trial (by 19 and 24 %, respectively, P <0·01 for both). There were no differences in lunch energy intake between trials. The present findings suggest that there may be an advantage for body fat regulation and lipid metabolism in exercising before compared with after breakfast. However, further study is needed to determine whether the present findings extend over the long term under free-living conditions.