Nonexercise energy expenditure and physical activity in the Midwest Exercise Trial 2

Aerobic exercise elevates perceived appetite but does not modify energy intake over a 3-day postexercise period: A pilot study

While a low degree of energy compensation is typically reported over the 24 h following a session of exercise, the prolonged impact of a bout of exercise on energy intake remains unclear. To overcome the challenge associated with accurately measuring energy intake in a free-living environment, this study employed the use of a meal replacement beverage to assess the 3 day impact of an exercise session on energy intake. In a randomized, crossover study, 14 participants (8 male, 6 female) completed two trials: (1) EX: 75 min exercise on a motorized treadmill (75% VO2peak); and (2) SED: 75 min sedentary control session. Each condition was followed by 3 days of exclusive ad libitum consumption of a meal replacement beverage. Appetite-regulating hormones, subjective appetite, energy intake, and energy expenditure were assessed. Exercise transiently suppressed the orexigenic hormone acyl-ghrelin (p < 0.05) and elevated the appetite-supressing hepatokine GDF-15 (p < 0.05). Despite these acute changes, overall perceived appetite was elevated over the 3 day assessment period with exercise (p < 0.05). No increase in energy intake or change in postexercise physical activity patterns were observed. One acute session of moderate to vigorous exercise is unlikely to affect short-term, three-day energy balance in healthy individuals.

Compensatory mechanisms from different exercise intensities in type 2 diabetes: a secondary analysis of a 1-year randomized controlled trial

AIMS

This investigation aimed to determine the effect of different intensities of training on non-exercise physical activity (NEPA) and estimated thermogenesis (NEAT) from a 1-year exercise randomized controlled trial (RCT) in individuals with type 2 diabetes mellitus (T2DM) on non-training days. Additionally, changes in NEPA and estimated NEAT in those who failed (low-responders) or succeeded (high-responders) in attaining exercise-derived clinically meaningful reductions in body weight (BW) and fat mass (FM) (i.e., 6% for FM and 3% for BW) was assessed.

METHODS

Individuals with T2DM (n = 80) were enrolled in a RCT with three groups: resistance training combined with moderate-intensity continuous training (MICT) or high-intensity interval training (HIIT) and a control group. Of the 80 participants, 56 (completed data) were considered for this secondary analysis. NEPA and estimated NEAT were obtained by accelerometry and body composition through dual-energy X-ray absorptiometry.

RESULTS

After adjustments, no time*group interactions were found for estimated NEAT in the MICT (β = - 5.33, p = 0.366) and HIIT (β = - 5.70, p = 0.283), as well as for NEPA in the MICT (β = - 452.83, p = 0.833) and HIIT (β = - 2770.76, p = 0.201), when compared to controls. No compensatory changes in NEPA and estimated NEAT were observed when considering both low-responders and high-responders to FM and BW when compared to controls.

CONCLUSIONS

Both MICT and HIIT did not result in any compensatory changes in estimated NEAT and NEPA with the intervention on non-training days. Moreover, no changes in estimated NEAT and NEPA were found when categorizing our participants as low-responders and high-responders to FM and BW when compared to controls. Trial registration clinicaltrials.gov ID. NCT03144505.

Altered motivation states for physical activity and 'appetite' for movement as compensatory mechanisms limiting the efficacy of exercise training for weight loss

Weight loss is a major motive for engaging in exercise, despite substantial evidence that exercise training results in compensatory responses that inhibit significant weight loss. According to the Laws of Thermodynamics and the CICO (Calories in, Calories out) model, increased exercise-induced energy expenditure (EE), in the absence of any compensatory increase in energy intake, should result in an energy deficit leading to reductions of body mass. However, the expected negative energy balance is met with both volitional and non-volitional (metabolic and behavioral) compensatory responses. A commonly reported compensatory response to exercise is increased food intake (i.e., Calories in) due to increased hunger, increased desire for certain foods, and/or changes in health beliefs. On the other side of the CICO model, exercise training can instigate compensatory reductions in EE that resist the maintenance of an energy deficit. This may be due to decreases in non-exercise activity thermogenesis (NEAT), increases in sedentary behavior, or alterations in sleep. Related to this EE compensation, the motivational states associated with the desire to be active tend to be overlooked when considering compensatory changes in non-exercise activity. For example, exercise-induced alterations in the wanting of physical activity could be a mechanism promoting compensatory reductions in EE. Thus, one's desires, urges or cravings for movement-also known as "motivation states" or "appetence for activity"-are thought to be proximal instigators of movement. Motivation states for activity may be influenced by genetic, metabolic, and psychological drives for activity (and inactivity), and such states are susceptible to fatigue-or reward-induced responses, which may account for reductions in NEAT in response to exercise training. Further, although the current data are limited, recent investigations have demonstrated that motivation states for physical activity are dampened by exercise and increase after periods of sedentarism. Collectively, this evidence points to additional compensatory mechanisms, associated with motivational states, by which impositions in exercise-induced changes in energy balance may be met with resistance, thus resulting in attenuated weight loss.

The Effects of an Acute Bout of Aerobic or Resistance Exercise on Nonexercise Physical Activity

Introduction/Purpose

A reduction in nonexercise physical activity (NEPA) after exercise may reduce the effectiveness of exercise interventions on weight loss in adults with overweight or obesity. Aerobic exercise (AEx) and resistance exercise (REx) may have different effects on NEPA. The purpose of this secondary analysis was to examine the effect of a single bout of AEx or REx on NEPA and sedentary behavior in inactive adults with overweight or obesity.

Methods

Adults with overweight or obesity (n = 24; 50% male; age, 34.5 ± 1.5 yr; body mass index, 28.5 ± 0.9 kg·m-2) not meeting current physical activity guidelines completed a single 45-min bout of AEx, REx, or a sedentary control on different days in random order. After each condition, participants' NEPA was recorded for 84 h by accelerometer. Time spent sedentary and in light, moderate, and vigorous physical activity; steps; metabolic equivalent of task (MET)-hours; and sit-to-stand transitions were calculated using activity count data.

Results

No differences were observed in the percent of waking time spent sedentary and in light, moderate, and vigorous activity between conditions (P > 0.05). No differences were observed in steps, MET-hours, or sit-to-stand transitions between conditions (P > 0.05). NEPA responses were variable among individuals, with approximately half of participants reducing and half increasing NEPA over the 84 h after each exercise condition.

Conclusion

NEPA was not reduced after an acute bout of AEx or REx in a sample of inactive adults with overweight or obesity.

The fire of evolution: energy expenditure and ecology in primates and other endotherms

Total energy expenditure (TEE) represents the total energy allocated to growth, reproduction and body maintenance, as well as the energy expended on physical activity. Early experimental work in animal energetics focused on the costs of specific tasks (basal metabolic rate, locomotion, reproduction), while determination of TEE was limited to estimates from activity budgets or measurements of subjects confined to metabolic chambers. Advances in recent decades have enabled measures of TEE in free-living animals, challenging traditional additive approaches to understanding animal energy budgets. Variation in lifestyle and activity level can impact individuals' TEE on short time scales, but interspecific differences in TEE are largely shaped by evolution. Here, we review work on energy expenditure across the animal kingdom, with a particular focus on endotherms, and examine recent advances in primate energetics. Relative to other placental mammals, primates have low TEE, which may drive their slow pace of life and be an evolved response to the challenges presented by their ecologies and environments. TEE variation among hominoid primates appears to reflect adaptive shifts in energy throughput and allocation in response to ecological pressures. As the taxonomic breadth and depth of TEE data expand, we will be able to test additional hypotheses about how energy budgets are shaped by environmental pressures and explore the more proximal mechanisms that drive intra-specific variation in energy expenditure.

Perspective: Is the Response of Human Energy Expenditure to Increased Physical Activity Additive or Constrained?

The idea that increasing physical activity directly adds to TEE in humans (additive model) has been challenged by the energy constrained hypothesis (constrained model). This model proposes that increased physical activity decreases other components of metabolism to constrain TEE. There is a logical evolutionary argument for trade-offs in metabolism, but, to date, evidence supporting constraint is subject to several limitations, including cross-sectional and correlational studies with potential methodological issues from extreme differences in body size/composition and lifestyle, potential statistical issues such as regression dilution and spurious correlations, and conclusions drawn from deductive inference rather than direct observation of compensation. Addressing these limitations in future studies, ideally, randomized controlled trials should improve the accuracy of models of human energy expenditure. The available evidence indicates that in many scenarios, the effect of increasing physical activity on TEE will be mostly additive although some energy appears to "go missing" and is currently unaccounted for. The degree of energy balance could moderate this effect even further. Adv Nutr 2023;x:xx-xx.

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.

Physical Activity and Total Daily Energy Expenditure in Older US Adults: Constrained versus Additive Models

PURPOSE

This study aimed to examine the shape of the relationship between physical activity (PA) and total energy expenditure (TEE) and to explore the role of energy balance status (negative, stable, positive) in influencing this association.

METHODS

Cross-sectional. Participants were 584 older adults (50-74 yr) participating in the Interactive Diet and Activity Tracking in AARP study. TEE was assessed by doubly labeled water and PA by accelerometer. The relationship between PA and TEE was assessed visually and using nonlinear methods (restricted cubic splines). Percent weight change (>3%) over a 6-month period was used as a proxy measurement of energy balance status.

RESULTS

TEE generally increased with increasing deciles of PA averaging 2354 (SD, 351) kcal·d-1 in the bottom decile to 2693 (SD, 480) kcal·d-1 in the top decile. Cubic spline models showed an approximate linear association between PA and TEE (linear relation, P < 0.0001; curvature, P = 0.920). Results were similar in subgroup analyses for individuals classified as stable or positive energy balance. For those in negative energy balance, TEE was generally flat with increasing deciles of PA averaging 2428 (SD, 285) kcal·d-1 in the bottom decile to 2372 (SD, 560) kcal·d-1 in the top decile.

CONCLUSIONS

Energy balance status seems to play an important role in the relationship between PA and TEE. When in a positive energy balance, the relationship between TEE and PA was consistent with an additive model; however, when energy balance was negative, TEE seems to be consistent with a constrained model. These findings support PA for weight gain prevention by increasing TEE; however, the effect of PA on TEE during periods of weight loss may be limited. An adequately powered, prospective study is warranted to confirm these exploratory findings.

The Mystery of Energy Compensation

AbstractThe received wisdom on how activity affects energy expenditure is that the more activity is undertaken, the more calories will have been burned by the end of the day. Yet traditional hunter-gatherers, who lead physically hard lives, burn no more calories each day than Western populations living in labor-saving environments. Indeed, there is now a wealth of data, both for humans and other animals, demonstrating that long-term lifestyle changes involving increases in exercise or other physical activities do not result in commensurate increases in daily energy expenditure (DEE). This is because humans and other animals exhibit a degree of energy compensation at the organismal level, ameliorating some of the increases in DEE that would occur from the increased activity by decreasing the energy expended on other biological processes. And energy compensation can be sizable, reaching many hundreds of calories in humans. But the processes that are downregulated in the long-term to achieve energy compensation are far from clear, particularly in humans-we do not know how energy compensation is achieved. My review here of the literature on relevant exercise intervention studies, for both humans and other species, indicates conflict regarding the role, if any, of basal metabolic rate (BMR) or low-level activity such as fidgeting play, particularly once changes in body composition are factored out. In situations where BMR and low-level activity are not major components of energy compensation, what then drives it? I discuss how changes in mitochondrial efficiency and changes in circadian fluctuations in BMR may contribute to our understanding of energy management. Currently unexplored, these mechanisms and others may provide important insights into the mystery of how energy compensation is achieved.

Effect of Combined Interval and Continuous Exercise Training on Gastric Emptying, Appetite, and Adaptive Responses in Men With Overweight and Obesity

Background/Objectives: Characterizing compensatory and adaptive responses to exercise assists in understanding changes in energy balance and health outcomes with exercise interventions. This study investigated the effects of a short-term exercise intervention (combining high intensity interval (HII) and continuous exercise) on (1) gastric emptying, appetite and energy intake; and (2) other adaptive responses including cardiorespiratory fitness, in inactive men with overweight/obesity. Methods: Fifteen men (BMI: 29.7 ± 3.3 kg/m-2) completed a 4-wk supervised exercise intervention, consisting of 5 exercise sessions per week alternating between HII (30 s at 100% VO2max followed by 30 s recovery) and continuous (at 50% VO2max) training on a cycle ergometer, progressing from 30 to 45 min session duration. Gastric emptying (13C-octanoic acid breath test), appetite (visual analog scale), energy intake (ad libitum lunch meal), body composition (air displacement plethysmography), non-exercise activity (accelerometery) VO2max, blood pressure, and fasting concentrations of glucose, insulin, and ghrelin were measured before and after (≥48 h) the intervention. Results: Gastric emptying, glucose, insulin and ghrelin were unchanged, but energy intake at the ad libitum lunch test meal significantly increased at post-intervention (+171 ± 116 kcal, p < 0.01). Body weight (-0.9 ± 1.1 kg), waist circumference (-2.3 ± 3.5 cm) and percent body fat (-0.9 ± 1.1%) were modestly reduced (P < 0.05). VO2max increased (+4.4 ± 2.1 ml.kg.min-1) by 13% and systolic (-6.2 ± 8.4 mmHg) and diastolic (-5.8 ± 2.2 mmHg) blood pressure were significantly reduced (P ≤ 0.01 for all). Conclusions: Four weeks of exercise training did not alter gastric emptying, indicating gastric emptying may only adapt to a higher volume/longer duration of exercise or changes in other characteristics associated with regular exercise. The combination of HII and continuous exercise training had beneficial effects on body composition, cardiorespiratory fitness, and blood pressure and warrants further investigation in larger randomized controlled trials.

Total energy expenditure (TEE) of young adults from urban South India: revisiting their daily energy requirement

BACKGROUND/OBJECTIVES

Young Indian adults are at greater risk of overweight/obesity due to their high energy intake and sedentary lifestyle. Their energy requirement (ER) is based on their total energy expenditure (TEE) estimated from factorial method, which possibly overestimates their basal metabolic rate (BMR) and physical activity level (PAL). This study aimed to compare the accurately measured TEE with ER in young adults. Secondarily, to compare measured with predicted BMR and guideline PAL with that obtained from questionnaire and step counts.

SUBJECTS/METHODS

TEE was measured in 19 male adults (18-30 years), using the doubly labeled water technique, over 14 days. Indirect calorimetry was used to measure BMR, while the PAL was estimated by (a) the ratio of measured TEE and BMR, (b) step counts over 7 days measured using tri-axial accelerometers and (c) a physical activity questionnaire (PAQ).

RESULTS

The measured TEE (9.11 ± 1.30 MJ/d) was significantly lower than the ER using either the Indian (15.2%) or the FAO/WHO/UNU (11.9%, both p < 0.01) recommendations. The measured BMR (6.90 ± 0.65 MJ/d) was significantly lower than that predicted using the FAO/WHO/UNU equation (6.5%, p < 0.01) but not for the Indian equation. The estimated PAL from measured TEE and BMR (1.35 ± 0.18), and from accelerometers (1.33 ± 0.11) was significantly lower than PAL obtained from PAQ (1.53 ± 0.17) or the guideline of 1.53 for Indians.

CONCLUSIONS

The predicted BMR and PAL guideline value was higher than that measured in young Indian adults, resulting in a ~13% lower measured TEE. This emphasizes the need to revisit the guidelines for predicting ER for this population.

Energy Compensation Following a Supervised Exercise Intervention in Women Living With Overweight/Obesity Is Accompanied by an Early and Sustained Decrease in Non-structured Physical Activity

Background/Objectives

Body composition (BC) does not always vary as a function of exercise induced energy expenditure (exercise EE – resting EE). Energy balance variables were measured to understand energy compensation (EC) in response to an exercise intervention performed at low (LOW) or moderate (MOD) intensity.

Subjects/Methods

Twenty-one women with overweight/obesity (33 ± 5 kg/m²; 29 ± 10 yrs; 31 ± 4 ml O₂/kg/min) were randomized to a 3-month LOW or MOD (40 or 60% of VȮ_2reserve, respectively) matched to expend 1500 kcal/week (compliance = 97 ± 5%). Body energy stores (DXA), energy intake (EI) (food menu and food diaries), resting EE (indirect calorimetry), total EE (doubly-labeled water), time spent in different activities (accelerometers), appetite (visual analog scale), eating behavior traits and food reward (liking and wanting) were assessed at baseline, after weeks 1 and 2 and at the end of the 3-month exercise intervention.

Results

EC based on BC changes (fat mass and fat-free mass) was 49 ± 79% and 161 ± 88% in LOW and MOD groups, respectively (p = 0.010). EI did not change significantly during the intervention. However, eating behavior traits and food reward had changed by the end of the 3-month supervised exercise. Non-structured physical activity (NSPA) decreased across the intervention (p < 0.002), independent of the intensity of the exercise training.

Conclusion

Women with overweight/obesity training at LOW presented lower EC for a given energy cost of exercise. Our results strongly suggest that NSPA plays a major role in mediating the effects of exercise on energy balance and ultimately on changes in BC.

Clinical Trial Registration

www.ClinicalTrials.gov, identifier ISRCTN31641049.

The effects of exercise session timing on weight loss and components of energy balance: midwest exercise trial 2

Background/objectives

Circadian physiology has been linked to body weight regulation and obesity. To date, few studies have assessed the association between exercise timing and weight related outcomes. The aim of this secondary analysis was to explore the impact of exercise timing (i.e., 24 h clock time of exercise session) on weight loss and components of energy balance.

Subjects/methods

Overweight/obese (BMI 25.0–39.9 kg/m²), physically inactive, young adults (~51% female) completed a 10-month supervised exercise program (400 or 600 kcal/session for 5 days/week) or served as non-exercise controls (CON). Participants were categorized based on the time of day in which they completed exercise sessions (Early-Ex: >50% of sessions completed between 7:00 and 11:59 am; (n = 21), Late-Ex: >50% of sessions completed between 3:00 and 7:00 pm; (n = 25), Sporadic-Ex: <50% of sessions completed in any time category; (n = 24), and CON; (n = 18)). Body weight, energy intake (EI; digital photography), and non-exercise physical activity (NEPA; accelerometer) were assessed at baseline, 3.5, 7, and 10 months. Total daily energy expenditure (TDEE; doubly labeled water), was assessed at baseline and 10 months.

Results

At month 10, weight loss was significantly greater in both Early-EX (−7.2 ± 1.2%; p < 0.001) and Sporadic-EX (− 5.5 ± 1.2%; p = 0.01) vs CON (+0.5 ± 1.0%), and Early-EX vs Late-EX (−2.1 ± 1.0%; p < 0.001). There were no between group differences for change in TDEE, EI, and non-exercise energy expenditure (P > 0.05). A significant group × time interaction (p = 0.02) was observed for NEPA (counts/min), however, after adjusting for multiple comparisons, group effects were no longer significant.

Conclusions

Despite minimal differences in components of energy balance, Early-EX lost significantly more weight compared with Late-Ex. Although the mechanisms are unclear, the timing of exercise may be important for body weight regulation.

Energy balance dynamics during short-term high-intensity functional training

CrossFit (CF; CrossFit Inc., Washington, DC, USA) is a form of high-intensity functional training that focuses on training across the entire spectrum of physical fitness. CF has been shown to improve a number of indicators of health but little information assessing energy balance exists. The purpose of the present study was to investigate energy balance during 1 week of CF training. Men and women (n = 21; mean ± SD; age, 43.5 ± 8.4 years; body mass index, 27.8 ± 4.9 kg·m−2), with ≥3 months CF experience, had body composition assessed via air displacement plethysmography before and after 1 week of CF training. Participants wore ActiHeart monitors to assess total energy expenditure (TEE), activity energy expenditure, and CF energy expenditure (CF EE). Energy intake was assessed from TEE and Δ body composition. CF EE averaged 605 ± 219 kcal per 72 ± 10 min session. Weekly CF EE was 2723 ± 986 kcal. Participants were in an energy deficit (TEE: 3674 ± 855 kcal·day−1; energy intake: 3167 ± 1401 kcal·day−1). Results of the present study indicate that CF training can account for a significant portion of daily activity energy expenditure. The weekly expenditure is within levels shown to induce clinically meaningful weight loss in overweight/obese populations.

How much exercise should be promoted to raise total daily energy expenditure and improve health?

Despite longstanding recognition of the benefits of a physically active lifestyle, there remains ambiguity regarding exactly how much exercise should be promoted to raise total energy expenditure (TEE) and improve health. This review provides a brief summary of the dose-response relationship between physical activity and relative risk of morbidity and mortality; mechanisms through which exercise drives an increase in TEE; the highest reported levels of TEE measured via doubly labelled water; and the potential impact of non-compliance and confounders in moderating the contribution of exercise to increase TEE. Cohort studies provide a compelling argument that 'more is better' regarding the exercise dose for increasing TEE, that increasing TEE is protective for health, and that this is mediated through increased cardiorespiratory fitness. However, growing evidence shows that ever increasing volumes of weekly physical activity may reverse the cost-benefit seen with more modest doses. Animal and human studies show that the elevation in TEE associated with increasing exercise volume is commonly less than expected, due to physiological confounders. Further, there is considerable evidence of behavioural non-compliance to planned exercise in all but the most highly motivated athletes. Therefore, inbuilt defence mechanisms may safeguard against TEE being elevated to maximum levels.

Use of Time and Energy on Exercise, Prolonged TV Viewing, and Work Days

INTRODUCTION

The goal of this study was to describe differences in time use and energy expenditure associated with exercise, prolonged TV viewing, and work days in a longitudinal study of older adults.

METHODS

Participants were 1,020 adults who completed previous-day recalls that provided a profile of the use of time in sedentary and physical activity. Time use and physical activity energy expenditure were predicted for each type of day (exercise, prolonged TV, work) using linear mixed models, adjusting for age, sex, season of the year, and day of the week. Data were collected in 2012-2013; analysis was completed in 2017.

RESULTS

Exercise days had less sedentary time (-0.37 hours/day) and light activity (-0.29 hours/day), and less household, work, and shopping activities, such that the increase in total physical activity energy expenditure on exercise days (2.83 MET-hours/day) was only about half that expended during exercise (5.98 MET-hours/day). Prolonged TV viewing days had more total sedentary time (0.86 hours/days) and less light (-0.45 hours/day) and moderate-vigorous intensity activity (-0.41 hours/day), and thus lower total physical activity energy expenditure (-2.43 MET-hours/day). Work days had less sleep (-0.91 hours/day) and more total sedentary time (1.32 hours/day).

CONCLUSIONS

Exercise days had more physical activity energy expenditure, but because of reductions in other activities, only about half of the energy expended during exercise was added to total daily physical activity energy expenditure. Prolonged TV viewing days had less physical activity energy expenditure and less moderate-vigorous activity. These findings provide new insights into possible compensation associated with exercise, and suggest a strong link between TV viewing and physical inactivity.

What is the effect of diet and/or exercise interventions on behavioural compensation in non-exercise physical activity and related energy expenditure of free-living adults? A systematic review

Non-exercise physical activity (NEPA) and/or non-exercise activity thermogenesis (NEAT) reductions may occur from diet and/or exercise-induced negative energy balance interventions, resulting in less-than-expected weight loss. This systematic review describes the effects of prescribed diet and/or physical activity (PA)/exercise on NEPA and/or NEAT in adults. Studies were identified from PubMed, web-of-knowledge, Embase, SPORTDiscus, ERIC and PsycINFO searches up to 1 March 2017. Eligibility criteria included randomised controlled trials (RCT), randomised trials (RT) and non-randomised trials (NRT); objective measures of PA and energy expenditure; data on NEPA, NEAT and spontaneous PA; ≥10 healthy male/female aged>18 years; and ≥7 d length. The trial is registered at PROSPERO-2017-CRD42017052635. In all, thirty-six articles (RCT-10, RT-9, NRT-17) with a total of seventy intervention arms (diet, exercise, combined diet/exercise), with a total of 1561 participants, were included. Compensation was observed in twenty-six out of seventy intervention arms (fifteen studies out of thirty-six reporting declines in NEAT (eight), NEPA (four) or both (three)) representing 63, 27 and 23 % of diet-only, combined diet/exercise, and exercise-only intervention arms, respectively. Weight loss observed in participants who decreased NEAT was double the weight loss found in those who did not compensate, suggesting that the energy imbalance degree may lead to energy conservation. Although these findings do not support the hypothesis that prescribed diet and/or exercise results in decreased NEAT and NEPA in healthy adults, the underpowered trial design and the lack of state-of-the-art methods may limit these conclusions. Future studies should explore the impact of weight-loss magnitude, energetic restriction degree, exercise dose and participant characteristics on NEAT and/or NEPA.

Energy expenditure responses to exercise training in older women

Previous studies have shown inconsistent findings regarding how structured exercise affects energy expenditure (EE). This study was designed to determine the changes in EE and physical activity following exercise training in older women. Nonobese (body mass index = 25.8 ± 3.4 kg·m-2) women (60-75 years, n = 72) completed a 4-month supervised aerobic exercise training of lower- or higher-dose (33.6 and 58.8 kJ·kg-1 body weight weekly, respectively) at 50-55% of heart rate reserve. Total daily EE (TDEE) by the doubly labeled water method, resting metabolic rate (RMR) via indirect calorimetry, and physical activity by accelerometer were determined before and at the end of exercise training. Nonexercise activity thermogenesis (NEAT) was calculated. Following exercise training, the changes in components of TDEE and total physical activity did not differ by group. In the entire sample, TDEE, RMR, NEAT and total physical activity did not change (P > 0.05 for all). However, a significant baseline physical activity × time interaction was found for several of the variables. Data were therefore stratified into tertiles of baseline physical activity. In the high tertile, TDEE remained unchanged, but total physical activity decreased (P = 0.012). In contrast, in the middle and low tertiles, NEAT remained unchanged, and total physical activity increased (P < 0.05 for both). In conclusion, aerobic exercise training did not change TDEE, RMR, NEAT, or total physical activity in this sample of older women. Exercise dose did not, but baseline physical activity levels might, influence EE responses and total physical activity changes.

Impact of 4 weeks of interval training on resting metabolic rate, fitness, and health-related outcomes

Resting metabolic rate (RMR) and substrate oxidation (respiratory exchange ratio; RER) are important indicators of health. The effects of interval training on RMR have not been thoroughly investigated, which was the purpose of the present study. Thirty men and women (mean ± SD age and maximal oxygen uptake: 28.8 ± 7.6 years and 33.0 ± 8.3 mL·kg^-1·min^-1) completed 4 weeks of Wingate-based sprint interval training (SIT), repeated 1-min high-intensity intervals (HIIT), or served as controls. Before and after training, RMR, resting RER, maximal oxygen uptake, body composition, physical activity, and energy intake were recorded. Data were analyzed using a repeated-measures ANOVA. RMR increased in response to 4 weeks of SIT training (1789 ± 293 to 1855 ± 320 kcal·day^-1; p = 0.003) but did not increase after HIIT (1670 ± 324 to 1704 ± 329 kcal·day^-1; p = 0.06). While SIT increased RMR by ∼2× the magnitude of HIIT, the difference was not significant (p = 0.5). Fasting substrate oxidation and RER did not change (p > 0.05). Maximal oxygen uptake increased, and small changes were also observed in percent body fat and fat mass (p < 0.05 for all). In conclusion, SIT provided a time-efficient stimulus to increase RMR after 4 weeks in healthy adults. However, the clinical relevance of the changes observed in this study remains to be determined. Further studies should be conducted in obese individuals and those with diabetes or insulin resistance to examine if interval training (≥4 weeks) influences resting metabolic rate in magnitudes similar to that reported here.

Sedentary behavior and compensatory mechanisms in response to different doses of exercise-a randomized controlled trial in overweight and obese adults

BACKGROUND/OBJECTIVES

To examine compensatory changes in sedentary behavior (SB) and light-intensity physical activities (LIPA) in response to a 22-week exercise training program in overweight/obese adults; and to determine if different forms of exercise training and physical activity recommendations interact with these compensatory changes.

SUBJECTS/METHODS

Eighty-nine overweight and obese individuals (body mass index (BMI): 25-34.9 kg/m², 48% males), aged 18-50 years, were randomized into four intervention groups (strength, endurance, combined strength + endurance and physical activity recommendations) with a 25-30% caloric restriction of total daily energy expenditure for 22 weeks. Energy expenditure was measured by accelerometry before, during and after the program.

RESULTS

LIPA increased significantly (P<0.001) after three months and at the end of intervention compared to baseline (pre: 281±9 min; 3 months: 303±9 min; post: 312±8 min). SB percentage decreased by 5.3 at the end of the intervention (P=0.002). No interactions were observed between groups or sexes. Significant correlations were found between SB and body weight, fat mass, android fat mass and lean body mass before and after the intervention (P<0.05). LIPA was also significantly correlated with all these body composition variables in the pre-intervention, but only correlated with body weight at the end of intervention.

CONCLUSIONS

There were no compensatory changes after a combined exercise and diet program; where minutes in LIPA increased and %SB decreased after the program, without differences among exercise modes. Greater physical activity levels can contribute to a better percentage and distribution of body tissues.

Dose–response effects of aerobic exercise on energy compensation in postmenopausal women: combined results from two randomized controlled trials

Background/objectives:

Despite the clear health benefits of exercise, exercised-induced weight loss is often less than expected. The term ‘exercise energy compensation’ is used to define the amount of weight loss below what is expected for the amount of exercise energy expenditure. We examined the dose–response effects of exercise volume on energy compensation in postmenopausal women.

Participants/methods:

Data from Alberta Physical Activity and Breast Cancer Prevention (ALPHA) and Breast Cancer and Exercise Trial in Alberta (BETA) were combined for the present analysis. The ALPHA and BETA trials were two-centred, two-armed, 12-month randomized controlled trials. The ALPHA trial included 160 participants randomized to 225 min per week of aerobic exercise, and the BETA trial randomized 200 participants to each 150 and 300 min per week of aerobic exercise. All participants were aged 50–74 years, moderately inactive (<90 min per week of exercise), had no previous cancer diagnosis and a body mass index between 22 and 40 kg m⁻². Energy compensation was based on changes in body composition (dual-energy X-ray absorptiometry scan) and estimated exercise energy expenditure from completed exercise volume. Associations between Δenergy intake, ΔVO_2peak and Δphysical activity time with energy compensation were assessed.

Results:

No differences in energy compensation were noted between interventions. However, there were large inter-individual differences in energy compensation between participants; 9.4% experienced body composition changes that were greater than expected based on exercise energy expenditure, 64% experienced some degree of energy compensation and 26.6% experienced weight gain based on exercise energy expenditure. Increases in VO_2peak were associated with reductions in energy compensation (β=−3.44 ml kg⁻¹ min⁻¹, 95% confidence interval for β=−4.71 to −2.17 ml kg⁻¹ min⁻¹; P=0.0001).

Conclusions:

Large inter-individual differences in energy compensation were noted, despite no differences between activity doses. In addition, increases in VO_2peak were associated with lower energy compensation. Future studies are needed to identify behavioral and metabolic factors that may contribute to this large inter-individual variability in energy compensation.

Obesity and energy balance: What is the role of physical activity?

Despite billions of dollars spent over decades of research, debate remains over the causes and solutions of the obesity epidemic. The specific role of physical activity in the prevention or treatment of obesity seems a particularly contentious issue, with opposing views put forth in both academic and popular media. In an attempt to provide context and clarity to the specific question of the role of physical activity in determination of body weight, we have attempted to identify evidence or lack thereof in the scientific literature and provide a summary of our findings. Areas covered: Topics included in this narrative review are an overview of energy balance, the relationship between physical activity and energy expenditure, compensatory responses in non-exercise energy expenditure and energy intake, and the relationship between physical activity and obesity. Expert commentary: Based on a review of the existing literature, daily physical activity and structured exercise has beneficial effects on an individual's body weight. In most instances, exercise occurring in adequate amounts will increase total daily energy expenditure and create an acute energy deficit, without compensatory decreases in non-exercise physical activity or energy expenditure nor compensatory increases in energy intake. Several gaps in the literature exist, both in terms of the number of adequately powered clinical trials with rigorous assessments of both energy intake and expenditure, and with a variety of study populations (by age, sex, race, etc.) and with varying exercise volumes and intensities.

Energy and Macronutrient Intake in the Midwest Exercise Trial 2 (MET-2)

PURPOSE

This study aimed to examine the effect of exercise training over 10 months at two levels of energy expenditure on energy and macronutrient intake in a sample of previously sedentary, overweight/obese young adults.

METHODS

We conducted a 10-month trial in 141 young adults who were randomized to either supervised exercise 5 d·wk(-1) at 400 and 600 kcal per session or nonexercise control. Participants were instructed to maintain their usual ad libitum diet. Energy/macronutrient intake was assessed at baseline and 3.5, 7, and 10 months over 7-d periods of ad libitum eating in a university cafeteria using digital photography. Foods consumed outside the cafeteria were assessed using multiple-pass recalls.

RESULTS

There were no significant between-group differences in absolute energy intake at baseline or at any other time point in the total sample or in men. In women, absolute energy intake was significantly greater in the 600-kcal-per-session group versus controls at both 3.5 and 7 months. There were no significant between-group differences in relative energy intake (kcal·kg·d(-1)) at any time point in the total sample, in men or women. There were no significant within- or between-group differences of change in absolute or relative energy intake in any of the three study groups in the total sample or in men or women. No clinically relevant changes in macronutrient intake were observed.

CONCLUSIONS

Aerobic exercise training does not significantly alter energy or macronutrient intake in overweight and obese young adults. The possibility of a threshold level beyond which increased exercise energy expenditure fails to produce a more negative energy balance and potential sex differences in the energy intake response to increased levels of exercise are potentially important.

Exercise volume and aerobic fitness in young adults: the Midwest Exercise Trial-2

To examine the effect of exercise volume at a fixed intensity on changes in aerobic fitness. Ninety-two overweight/obese individuals (BMI 25-40 kg m(2)), age 18-30 years, 50 % women, completed a 10 mo, 5 d wk(-1) supervised exercise intervention at 2 levels of exercise energy expenditure (400 or 600 kcal session(-1)) at 70-80 % heart rate (HR) max. Exercise consisted primarily of walking/jogging on motor-driven treadmills. The duration and intensity of all exercise sessions were verified by a downloadable HR monitor set to collect HR in 1-min epochs. All participants were instructed to continue their typical patterns of non-exercise physical activity and dietary intake over the duration of the 10 mo intervention. Maximal aerobic capacity (indirect calorimetry) was assessed on a motor-driven treadmill using a modified Balke protocol at baseline, mid-point (5 mo), and following completion of the 10 mo intervention. VO2 max (L min(-1)) increased significantly in both the 400 (11.3 %) and 600 kcal session(-1) groups (14 %) compared to control (-2.0 %; p < 0.001); however, the differences between exercise groups were not significant. Similar results were noted for change in relative VO2 max (mL kg(-1) min(-1)); however, the magnitude of change was greater than for absolute VO2 max (L min(-1)) (400 group = 18.3 %; 600 group = 20.2 %) due to loss of body weight over the 10-mo intervention in both exercise groups. Our results indicate that exercise volume was not associated with change in aerobic fitness in a sample of previously sedentary, overweight and obese young adults.

Change in energy expenditure and physical activity in response to aerobic and resistance exercise programs

Exercise is considered an important component of a healthy lifestyle but there remains controversy on effects of exercise on non-exercise physical activity (PA). The present study examined the prospective association of aerobic and resistance exercise with total daily energy expenditure and PA in previously sedentary, young men. Nine men (27.0 ± 3.3 years) completed two 16-week exercise programs (3 exercise sessions per week) of aerobic and resistance exercise separated by a minimum of 6 weeks in random order. Energy expenditure and PA were measured with the SenseWear Mini Armband prior to each intervention as well as during week 1, week 8 and week 16 of the aerobic and resistance exercise program. Body composition was measured via dual x-ray absorptiometry. Body composition did not change in response to either exercise intervention. Total daily energy expenditure on exercise days increased by 443 ± 126 kcal/d and 239 ± 152 kcal/d for aerobic and resistance exercise, respectively (p < 0.01). Non-exercise moderate-to-vigorous PA, however, decreased on aerobic exercise days (−148 ± 161 kcal/d; p = 0.03). There was no change in total daily energy expenditure and PA on non-exercise days with aerobic exercise while resistance exercise was associated with an increase in moderate-to-vigorous PA during non-exercise days (216 ± 178 kcal/d, p = 0.01). Results of the present study suggest a compensatory reduction in PA in response to aerobic exercise. Resistance exercise, on the other hand, appears to facilitate non-exercise PA, particularly on non-exercise days, which may lead to more sustainable adaptations in response to an exercise program.

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.

Energy intake, nonexercise physical activity, and weight loss in responders and nonresponders: The Midwest Exercise Trial 2

OBJECTIVE

To compare energy intake, total daily energy expenditure (TDEE), nonexercise energy expenditure (NEEx), resting metabolic rate (RMR), nonexercise physical activity (NEPA), and sedentary time between participants with weight loss <5% (nonresponders) vs. ≥5% (responders) in response to exercise.

METHODS

Adults (18-30 years) with overweight/obesity (BMI 25-40 kg/m(2) ) were randomized to exercise: 5 days/week, 400 or 600 kcal/session, 10 months.

RESULTS

Of the participants, 40 responded and 34 did not respond to the exercise protocol. Nonresponder energy intake was higher vs. responders, significant only in men (P=0.034). TDEE increased only in responders (P=0.001). NEEx increased in responders and decreased in nonresponders, significant only in men (P=0.045). There were no within- or between-group differences for change in RMR. NEPA increased in responders and decreased in nonresponders (group-by-time interactions: total sample, P=0.049; men, P=0.016). Sedentary time decreased in both groups, significant only in men.

CONCLUSIONS

Men who did not lose weight in response to exercise (<5%) had higher energy intake and lower NEEx when compared with men losing ≥5%. No significant differences in any parameters assessed were observed between women who lost <5% vs. those losing ≥5%. Factors associated with the weight loss response to exercise in women warrant additional investigation.

Validity of energy intake estimated by digital photography plus recall in overweight and obese young adults

BACKGROUND

Recent reports have questioned the adequacy of self-report measures of dietary intake as the basis for scientific conclusions regarding the associations of dietary intake and health, and reports have recommended the development and evaluation of better methods for the assessment of dietary intake in free-living individuals. We developed a procedure that used pre- and post-meal digital photographs in combination with dietary recalls (DP+R) to assess energy intake during ad libitum eating in a cafeteria setting.

OBJECTIVE

To compare mean daily energy intake of overweight and obese young adults assessed by a DP+R method with mean total daily energy expenditure assessed by doubly labeled water (TDEE(DLW)).

METHODS

Energy intake was assessed using the DP+R method in 91 overweight and obese young adults (age = 22.9±3.2 years, body mass index [BMI; calculated as kg/m(2)]=31.2±5.6, female=49%) over 7 days of ad libitum eating in a university cafeteria. Foods consumed outside the cafeteria (ie, snacks, non-cafeteria meals) were assessed using multiple-pass recall procedures, using food models and standardized, neutral probing questions. TDEE(DLW) was assessed in all participants over the 14-day period.

RESULTS

The mean energy intakes estimated by DP+R and TDEE(DLW) were not significantly different (DP+R=2912±661 kcal/d; TDEE(DLW)=2849±748 kcal/d, P=0.42). The DP+R method overestimated TDEE(DLW) by 63±750 kcal/d (6.8±28%).

CONCLUSION

Results suggest that the DP+R method provides estimates of energy intake comparable to those obtained by TDEE(DLW).