No consistent evidence of a disproportionately low resting energy expenditure in long-term successful weight-loss maintainers

Adaptive thermogenesis, at the level of resting energy expenditure, after diet alone or diet plus bariatric surgery

OBJECTIVE

The objective of this study was to compare the magnitude of adaptive thermogenesis (AT), at the level of resting energy expenditure (REE), after a very low-energy diet alone or combined with Roux-en-Y gastric bypass or sleeve gastrectomy, as well as to investigate the association between AT and changes in appetite.

METHODS

A total of 44 participants with severe obesity underwent 10 weeks of a very low-energy diet alone or combined with Roux-en-Y gastric bypass or sleeve gastrectomy. Body weight and composition, REE, subjective appetite feelings, and plasma concentrations of gastrointestinal hormones were measured at baseline and week 11. AT, at the level of REE, was defined as a significantly lower measured versus predicted (using a regression model with baseline data) REE.

RESULTS

Participants lost 18.4 ± 3.9 kg of body weight and experienced AT, at the level of REE (-121 ± 188 kcal/day; p < 0.001), with no differences among groups. The larger the AT, at the level of REE, the greater the reduction in fasting ghrelin concentrations and the smaller the reduction in feelings of hunger and desire to eat in the postprandial state.

CONCLUSIONS

Weight-loss modality does not seem to modulate the magnitude of AT, at the level of REE. The greater the AT, at the level of REE, the greater the drive to eat following weight loss.

Appetitive and Metabolic Responses to an Exercise versus Dietary Intervention in Adults with Obesity

Introduction/Purpose

Dietary restriction (DIET) and aerobic exercise (AEX) interventions may impact energy balance differently. Our aim was to describe the effects of weight loss interventions via DIET or AEX on measures of energy balance.

Methods

Adults with overweight or obesity were randomized to 12 weeks of DIET or AEX with similar calorie deficit goals. A study day was conducted before and after the intervention to assess subjective and hormonal (ghrelin, peptide-YY, glucagon-like peptide-1) appetite responses to a control meal, ad libitum energy intake (EI) at a single meal, and over three days of free-living conditions and eating behavior traits. Resting metabolic rate (RMR) was measured with indirect calorimetry and adjusted for body composition measured by dual X-ray absorptiometry. Non-exercise activity was measured using accelerometers.

Results

Forty-four individuals were included (age: 37 ± 9 years, body mass index: 30.6 ± 3.1 kg/m2). Both interventions resulted in weight and fat mass loss. The DIET group lost fat-free mass, although differences between groups were not significant (DIET: -1.2 ± 1.7 kg, p<0.001; AEX: 0.4 ± 1.5 kg, p=0.186; p=0.095 interaction). There were no differences in RMR after body composition adjustment. Both interventions were associated with an increase in dietary restraint (DIET: 4.9 ± 1.2, AEX: 2.8 ± 0.7; p<0.001 in both groups). Hunger decreased with DIET (-1.4 ± 0.5, p=0.003), and disinhibition decreased with AEX (-1.5 ± 0.5, p<0.001), although these changes were not different between groups (i.e., no group × time interaction). No other differences in appetite, EI, or non-exercise physical activity were observed within or between groups.

Conclusions

AEX did not result in compensatory alterations in appetite, ad libitum EI, or physical activity, despite assumed increased energy expenditure. Modest evidence also suggested that disinhibition and hunger may be differentially impacted by weight loss modality.

Metabolic adaptation delays time to reach weight loss goals

OBJECTIVE

The aim of this study was to determine whether metabolic adaptation, at the level of resting metabolic rate, was associated with time to reach weight loss goals, after adjusting for confounders.

METHODS

A total of 65 premenopausal women with overweight (BMI: 28.6 ± 1.5 kg/m2 ; age: 36.4 ± 5.9 years; 36 were White, and 29 were Black) followed an 800-kcal/d diet until BMI ≤25 kg/m2 . Body weight and composition were measured at baseline and after weight loss. Dietary adherence was calculated from total energy expenditure, determined by double labeled water, and body composition changes. Metabolic adaptation was defined as a significantly lower measured versus predicted resting metabolic rate (from own regression model). A regression model to predict time to reach weight loss goals was developed including target weight loss, energy deficit, dietary adherence, and metabolic adaptation as predictors.

RESULTS

Participants lost on average 12.5 ± 3.1 kg (16.1% ± 3.4%) over 155.1 ± 49.2 days. Average dietary adherence was 63.6% ± 31.0%. There was significant metabolic adaptation after weight loss (-46 ± 113 kcal/d, p = 0.002) and this variable was a significant predictor of time to reach weight loss goals (β = -0.1, p = 0.041), even after adjusting for confounders (R2 adjusted = 0.63, p < 0.001).

CONCLUSION

In premenopausal women with overweight, metabolic adaptation after a 16% weight loss increases the length of time necessary to achieve weight loss goals.

Weight and body composition changes affect resting energy expenditure predictive equations during a 12-month weight-loss intervention

OBJECTIVE

Mathematical equations that predict resting energy expenditure (REE) are widely used to derive calorie prescriptions during weight-loss interventions. Although such equations are known to introduce group- and individual-level error into REE prediction, their validity has largely been assessed in weight-stable populations. Therefore, this study sought to characterize how weight change affects the validity of commonly used REE predictive models throughout a 12-month weight-loss intervention.

METHODS

Changes in predictive error of four models (Mifflin-St-Jeor, Harris-Benedict, Owen, and World Health Organization/Food and Agriculture) were assessed at 1-, 6-, and 12-month time points in adults (n = 66, 76% female, aged 18-55 years, BMI = 27-45 kg/m² ) enrolled in a randomized clinical weight-loss trial.

RESULTS

All equations experienced significant negative shifts in bias (measured - predicted REE) toward overprediction from baseline to 1 month (p < 0.05). Three equations showed reversal of bias in the positive direction (toward underprediction) from baseline to 12 months (p < 0.05). Early changes in bias were correlated with decreased fat-free mass (p ≤ 0.01).

CONCLUSIONS

Changes in body composition and mass during a 12-month weight-loss intervention significantly affected REE predictive error in adults with overweight and obesity. Weight history should be considered when using mathematical models to predict REE during periods of weight fluctuation.

Temporal patterns of physical activity in successful weight loss maintainers

BACKGROUND/OBJECTIVES

Individuals successful at weight loss maintenance engage in high amounts of physical activity (PA). Understanding how and when weight loss maintainers accumulate PA within a day and across the week may inform PA promotion strategies and recommendations for weight management.

METHODS

We compared patterns of PA in a cohort of weight loss maintainers (WLM, n = 28, maintaining ≥13.6 kg weight loss for ≥1 year, BMI 23.6 ± 2.3 kg/m²), controls without obesity (NC, n = 30, BMI similar to current BMI of WLM, BMI 22.8 ± 1.9 kg/m²), and controls with overweight/obesity (OC, n = 26, BMI similar to pre-weight loss BMI of WLM, 33.6 ± 5.1 kg/m²). PA was assessed during 7 consecutive days using the activPAL^TM activity monitor. The following variables were quantified; sleep duration, sedentary time (SED), light-intensity PA (LPA), moderate-to-vigorous intensity PA (MVPA), and steps. Data were examined to determine differences in patterns of PA across the week and across the day using mixed effect models.

RESULTS

Across the week, WLM engaged in ≥60 min of MVPA on 73% of days, significantly more than OC (36%, p < 0.001) and similar to NC (59%, p = 0.10). Across the day, WLM accumulated more MVPA in the morning (i.e., within 3 h of waking) compared to both NC and OC (p < 0.01). WLM engaged in significantly more MVPA accumulated in bouts ≥10 min compared to NC and OC (p < 0.05). Specifically, WLM engaged in more MVPA accumulated in bouts of ≥60 min compared to NC and OC (p < 0.05).

CONCLUSIONS

WLM engage in high amounts of MVPA (≥60 min/d) on more days of the week, accumulate more MVPA in sustained bouts, and accumulate more MVPA in the morning compared to controls. Future research should investigate if these distinct patterns of PA help to promote weight loss maintenance.

Association between ketosis and metabolic adaptation at the level of resting metabolic rate

BACKGROUND

The ketone body β-hydroxybutyrate (βHB) has been shown to act as a signaling molecule that regulates metabolism and energy homeostasis during starvation in animal models. A potential association between βHB and metabolic adaptation (a reduction in energy expenditure below predicted levels) in humans has never been explored.

OBJECTIVE

To determine if metabolic adaptation at the level of resting metabolic rate (RMR) was associated with the magnitude of ketosis induced by a very-low energy diet (VLED). A secondary aim was to investigate if the association was modulated by sex.

METHODS

Sixty-four individuals with obesity (BMI: 34.5 ± 3.4 kg/m²; age: 45.7 ± 8.0 years; 31 males) enrolled in a 1000 kcal/day diet for 8 weeks. Body weight/composition, RMR and βHB (as a measure of ketosis) were determined at baseline and week 9 (W9). Metabolic adaptation was defined as a significantly lower measured versus predicted RMR (from own regression model).

RESULTS

Participants lost on average 14.0 ± 3.9 kg and were ketotic (βHB: 0.76 ± 0.51 mM) at W9. A significant metabolic adaptation was seen (-84 ± 106 kcal/day, P < 0.001), with no significant differences between sexes. [βHB] was positively correlated with the magnitude of metabolic adaptation in females (r = 0.432, P = 0.012, n = 33), but not in males (r = 0.089, P = 0.634, n = 31).

CONCLUSION

In females with obesity, but not males, the larger the [βHB] under VLED, the greater the metabolic adaptation at the level of RMR. More studies are needed to confirm these findings and to explore the mechanisms behind the sex difference in the association between ketosis and metabolic adaptation.

TRIAL REGISTRATION NAME

Clinicaltrials.gov.

STUDY REGISTRATION ID

NCT02944253. URL: https://clinicaltrials.gov/ct2/show/NCT02944253.

Metabolic adaptation is associated with less weight and fat mass loss in response to low-energy diets

BACKGROUND

The practical relevance of metabolic adaptation remains a controversial issue. To the best of our knowledge, no study has properly evaluated the role of metabolic adaptation in modulating weight loss outcomes. Therefore, the aim of this study was to determine the association between metabolic adaptation, at the level of resting metabolic rate (RMR), and weight and fat mass (FM) loss after low-energy diets (LED), after adjusting for dietary adherence and other confounders.

METHODS

71 individuals with obesity (BMI: 34.6 ± 3.4 kg/m2; age: 45.4 ± 8.2 years; 33 males) were randomized to one of three 1000 kcal/day diets for 8 weeks. Body weight, FM and fat-free mass (FFM) (air displacement plethysmography), RMR (indirect calorimetry) and physical activity level (PAL) (armbands) were measured at baseline and at week 9. Metabolic adaptation at week 9 was defined as measured RMR minus predicted RMR at week 9. An equation to predict RMR was derived from baseline data of all participants that were part of this analysis and included age, sex, FM and FFM as predictors. Dietary adherence was calculated from RMR, PAL and body composition changes. Linear regression was used to assess the potential role of metabolic adaptation in predicting weight and FM loss after adjusting for dietary adherence, average PAL, sex, baseline FM and FFM and randomization group.

RESULTS

Participants lost on average 14 ± 4 kg of body weight (13 ± 3%) and presented with metabolic adaptation (-92 ± 110 kcal/day, P < 0.001). Metabolic adaptation was a significant predictor of both weight (β = -0.009, P < 0.001) and FM loss (β = -0.008, P < 0.001), even after adjusting for confounders (R2 = 0.88, 0.93, respectively, P < 0.001 for both). On average, an increase in metabolic adaptation of 50 kcal/day was associated with a 0.5 kg lower weight and FM loss in response to the LED.

CONCLUSION

In individuals with obesity, metabolic adaptation at the level of RMR is associated with less weight and FM loss in response to LED. Trial registration ID: NCT02944253.

Underreporting of energy intake in weight loss maintainers

BACKGROUND

Individuals with overweight or obesity commonly underreport energy intake (EI), but it is unknown if the tendency to underreport persists in formerly obese individuals who lose significant weight and maintain their weight loss over long periods of time.

OBJECTIVE

Assess the accuracy of self-reported EI in successful weight loss maintainers (WLM) compared with controls of normal body weight (NC) and controls with overweight/obesity (OC).

METHODS

Participants for this case-controlled study were recruited in 3 groups: WLM [n = 26, BMI (in kg/m2) 24.1 ± 2.3; maintaining ≥13.6 kg weight loss for ≥1 y], NC (n = 33, BMI 22.7 ± 1.9; similar to current BMI of WLM), and OC (n = 32, BMI 34.0 ± 4.6; similar to pre-weight loss BMI of WLM). Total daily energy expenditure (TDEE) was measured over 7 d using the doubly labeled water (DLW) method, and self-reported EI was concurrently measured from 3-d diet diaries. DLW TDEE and self-reported EI were compared to determine accuracy of self-reported EI.

RESULTS

WLM underreported EI (median, interquartile range) (-605, -915 to -314 kcal/d) to a greater degree than NC (-308, -471 to -68 kcal/d; P < 0.01) but not more than OC (-310, -970 to 18 kcal/d; P = 0.21). WLM also showed a greater degree of relative underreporting (-25.3%, -32.9% to -12.5%) compared with NC (-14.3%, -19.6% to -3.1%; P = 0.02) but not OC (-11.2%, -34.1% to -0.7%; P = 0.16). A greater proportion of WLM was classified as underreporters (30.8%) than NC (9.1%; P = 0.05) but not OC (28.1%; P = 1.00).

CONCLUSIONS

WLM underreported EI in both absolute and relative terms to a greater extent than NC but not OC. These findings call into question the accuracy of self-reported EI in WLM published in previous studies and align with recent data suggesting that WLM rely less on chronic EI restriction and more on high levels of physical activity to maintain weight loss. This trial was registered at clinicaltrials.gov as NCT03422380.

Resting Energy Expenditure: From Cellular to Whole-Body Level, a Mechanistic Historical Perspective

The basis of heat generated by the human body has been a source of speculation and research for more than 2,000 years. Basal heat production, now usually referred to as resting energy expenditure (REE), is currently recognized as deriving from biochemical reactions at subcellular and cellular levels that are expressed in the energy expended by the body's 78 organs and tissues. These organs and tissues, and the 11 systems to which they belong, influence body size and shape. Connecting these subcellular-/cellular-level reactions to organs and tissues, and then on to body size and shape, provides a comprehensive understanding of individual differences in REE, a contemporary topic of interest in obesity research and clinical practice. This review critically examines these linkages, their association with widely used statistical and physiological REE prediction formulas, and often-unappreciated aspects of measuring basal heat production in humans.

Recent Advances in Hypertension: Intersection of Metabolic and Blood Pressure Regulatory Circuits in the Central Nervous System

Obesity represents the single greatest ongoing roadblock to improving cardiovascular health. Prolonged obesity is associated with fundamental changes in the integrative control of energy balance, including the development of selective leptin resistance, which is thought to contribute to obesity-associated hypertension, and adaptation of resting metabolic rate (RMR) when excess weight is reduced. Leptin and the melanocortin system within the hypothalamus contribute to the control of both energy balance and blood pressure. While the development of drugs to stimulate RMR and thereby reverse obesity through activation of the melanocortin system has been pursued, most of the resulting compounds simultaneously cause hypertension. Evidence supports the concept that although feeding behaviors, RMR, and blood pressure are controlled through mechanisms that utilize similar molecular mediators, these mechanisms exist in anatomically dissociable networks. New evidence supports a major change in molecular signaling within AgRP (Agouti-related peptide) neurons of the arcuate nucleus of the hypothalamus during prolonged obesity and the existence of multiple distinct subtypes of AgRP neurons that individually contribute to control of feeding, RMR, or blood pressure. Finally, ongoing work by our laboratory and others support a unique role for AT₁ (angiotensin II type 1 receptor) within one specific subtype of AgRP neuron for the control of RMR. We propose that understanding the unique biology of the AT₁-expressing, RMR-controlling subtype of AgRP neurons will help to resolve the selective dysfunctions in RMR control that develop during prolonged obesity and potentially point toward novel druggable antiobesity targets that will not simultaneously cause hypertension.

Exercise and the Cisd2 Prolongevity Gene: Two Promising Strategies to Delay the Aging of Skeletal Muscle

Aging is an evolutionally conserved process that limits life activity. Cellular aging is the result of accumulated genetic damage, epigenetic damage and molecular exhaustion, as well as altered inter-cellular communication; these lead to impaired organ function and increased vulnerability to death. Skeletal muscle constitutes ~40% of the human body’s mass. In addition to maintaining skeletal structure and allowing locomotion, which enables essential daily activities to be completed, skeletal muscle also plays major roles in thermogenesis, metabolism and the functioning of the endocrine system. Unlike many other organs that have a defined size once adulthood is reached, skeletal muscle is able to alter its structural and functional properties in response to changes in environmental conditions. Muscle mass usually remains stable during early life; however, it begins to decline at a rate of ~1% year in men and ~0.5% in women after the age of 50 years. On the other hand, different exercise training regimens are able to restore muscle homeostasis at the molecular, cellular and organismal levels, thereby improving systemic health. Here we give an overview of the molecular factors that contribute to lifespan and healthspan, and discuss the effects of the longevity gene Cisd2 and middle-to-old age exercise on muscle metabolism and changes in the muscle transcriptome in mice during very old age.

Metabolic adaptation is an illusion, only present when participants are in negative energy balance

BACKGROUND

The existence of metabolic adaptation, following weight loss, remains a controversial issue. To our knowledge, no study has evaluated the role of energy balance (EB) in modulating metabolic adaptation.

OBJECTIVES

The aim of this study was to determine if metabolic adaptation, at the level of resting metabolic rate (RMR), is modulated by participants' EB status. A secondary aim was to investigate if metabolic adaptation was associated with weight regain.

METHODS

Seventy-one individuals with obesity (BMI: 34.6 ± 3.4 kg/m2; age: 45.4 ± 8.2 y; 33 men) enrolled in a 1000-kcal/d diet for 8 wk, followed by 4 wk of weight stabilization and a 9-mo weight loss maintenance program. Body weight/composition and RMR were measured at baseline, week 9 (W9), week 13 (W13), and 1 y (1Y). Metabolic adaptation was defined as a significantly different (lower or higher) measured compared with predicted RMR.

RESULTS

Participants lost on average 14 kg by W9, followed by weight stabilization at W13, and regained 29% of their initial weight loss at 1Y. Metabolic adaptation was found at W9 (-92 ± 110 kcal/d, P < 0.001) and W13 (-38 ± 124 kcal/d, P = 0.011) but was not correlated with weight regain. A significant reduction in metabolic adaptation was seen between W9 and W13 (-53 ± 101 kcal/d, P < 0.001). In a subset of participants who gained weight between W9 and W13 (n = 33), no metabolic adaptation was seen at W13 (-26.8 ± 121.5 kcal/d, P = 0.214). In a subset of participants with data at all time points (n = 45), metabolic adaptation was present at W9 and W13 (-107 ± 102 kcal/d, P < 0.001 and -49 ± 128 kcal/d, P = 0.013) but not at 1Y (-7 ± 129, P = 0.701).

CONCLUSION

After weight loss, metabolic adaptation at the level of RMR is dependent on the EB status of the participants, being reduced to half after a period of weight stabilization. Moreover, metabolic adaptation does not predict weight regain at 1Y follow-up. These trials were registered at clinicaltrials.gov as NCT02944253 and NCT03287726.

Revisiting the Compensatory Theory as an explanatory model for relapse in obesity management

Weight regain remains the main challenge in obesity management, and its etiology remains elusive. The aim of the present review was to revise the available evidence regarding the "Compensatory Theory," which is an explanatory model of relapse in obesity treatment, and to propose alternative mechanisms that can contribute to weight regain. It has been proposed, and generally accepted as true, that when a person loses weight the body fights back, with physiological adaptations on both sides of the energy balance equation that try to bring body weight back to its original state: this is the Compensatory Theory. This theory proposes that the increased orexigenic drive to eat and the reduced energy expenditure that follow weight loss are the main drivers of relapse. However, evidence showing a link between these physiological adaptations to weight loss and weight regain is lacking. Here, we propose that the physiological adaptations to weight loss, both at the level of the homeostatic appetite control system and energy expenditure, are in fact a normalization to a lower body weight and not drivers of weight regain. In light of this we explore other potential mechanisms, both physiological and behavioral, that can contribute to the high incidence of relapse in obesity management. More research is needed to clearly ascertain whether the changes in energy expenditure and homeostatic appetite markers seen in reduced-obese individuals are a compensatory mechanism that drives relapse or a normalization towards a lower body weight, and to explore alternative hypotheses that explain relapse in obesity management.

Metabolic adaptation is not a major barrier to weight-loss maintenance

BACKGROUND

The existence of metabolic adaptation, at the level of resting metabolic rate (RMR), remains highly controversial, likely due to lack of standardization of participants' energy balance. Moreover, its role as a driver of relapse remains unproven.

OBJECTIVE

The main aim was to determine if metabolic adaptation at the level of RMR was present after weight loss and at 1- and 2-y follow-up, with measurements taken under condition of weight stability. A secondary aim was to investigate race differences in metabolic adaptation after weight loss and if this phenomenon was associated with weight regain.

METHODS

A total of 171 overweight women [BMI (kg/m2): 28.3 ± 1.3; age: 35.2 ± 6.3 y; 88 whites and 83 blacks] enrolled in a weight-loss program to achieve a BMI <25, and were followed for 2 y. Body weight and composition (4-compartment model) and RMR (indirect calorimetry) were measured after 4 wk of weight stability at baseline, after weight loss and at 1 and 2 y. Metabolic adaptation was defined as a significantly lower measured compared with predicted RMR (from own regression model).

RESULTS

Participants lost, on average, 12 ± 2.6 kg and regained 52% ± 38% and 89% ± 54% of their initial weight lost at 1 and 2 y follow-up, respectively. Metabolic adaptation was found after weight loss (-54 ± 105 kcal/d; P < 0.001), with no difference between races and was positively correlated with fat-mass loss, but not with weight regain, overall. In a subset of women (n = 46) with data at all time points, metabolic adaptation was present after weight loss, but not at 1- or 2-y follow-up (-43 ± 119, P = 0.019; -18 ± 134, P = 0.380; and - 19 ± 166, P = 0.438 kcal/day respectively).

CONCLUSIONS

In overweight women, metabolic adaptation at the level of RMR is minimal when measurements are taken under conditions of weight stability and does not predict weight regain up to 2 years follow-up.The JULIET study is registered at https://clinicaltrials.gov/ct2/show/NCT00067873 as NCT00067873.

Successful weight loss maintenance: A systematic review of weight control registries

Weight loss maintenance is a major challenge for obesity treatment. Weight control registries can be useful in identifying psychological and behavioural factors that could contribute to better long-term success. The objective of this study is to describe the existing weight control registries and their participants and identify correlates of weight loss maintenance. A comprehensive search of peer-reviewed articles published until November 2018 was conducted in PubMed, Web of Science, and Scopus. Studies that reported results from weight control registries were considered. Fifty-two articles, corresponding to five registries (the United States, Portugal, Germany, Finland, and Greece), were included. Registries differed in inclusion criteria and procedures. Of 51 identified weight loss and maintenance strategies, grouped in 14 domains of the Oxford Food and Activity Behaviors taxonomy, the following were the most frequently reported: having healthy foods available at home, regular breakfast intake, increasing vegetable consumption, decreasing sugary and fatty foods, limiting certain foods, and reducing fat in meals. Increased physical activity was the most consistent positive correlate of weight loss maintenance. To our knowledge, this is the first systematic review of information about successful weight loss maintenance obtained from weight control registries. Key common influential characteristics of success were identified, which can inform future prospective studies and weight management initiatives.

Associations of appetite sensations and metabolic characteristics with weight retention in postpartum women

Postpartum weight retention (PPWR) is an important risk factor for long-term obesity. Appetite may be a key factor regulating PPWR. The objectives of this study were to determine the associations between (i) PPWR and appetite; and (ii) appetite, lactation, and metabolic characteristics. Data from 49 women at 9 months postpartum contributed to this cross-sectional analysis. Energy expenditure was assessed in a whole-body calorimetry unit for 24 h. Appetite sensations were rated using visual analogue scales. Lactation (min/day) was measured using a 3-day breastfeeding diary. PPWR was negatively associated with fullness (β ± SE; R² = -2.97 ± 0.72; 0.661; P < 0.001), and satiety (-2.75 ± 0.81; 0.617; P = 0.002), and was positively associated with hunger (2.19 ± 1.02; 0.548; P = 0.039), prospective food consumption (PFC; 2.19 ± 0.91; 0.562; P = 0.021), and composite appetite score (CAS; 0.34 ± 0.09; 0.632; P = 0.001). Lactation was associated with higher CAS (39.68 ± 15.56; 0.365; P = 0.015), hunger (3.56 ± 1.61; 0.308; P = 0.033), and PFC (4.22 ± 1.78; 0.314; P = 0.023), and with reduced sensations of fullness (-4.18 ± 1.94; 0.358; P = 0.038) and satiety (-3.83 ± 1.87; 0.295; P = 0.048). Lactation was associated with appetite, which in turn was related to PPWR. Appetite control should be explored to support postpartum weight management strategies. Novelty Postpartum weight retention was associated with appetite sensations, which were assessed throughout the day under conditions in which energy intake and expenditure were precisely matched. Lactation and other maternal metabolic factors, including carbohydrate oxidation and physical activity level may play a role in controlling appetite during the postpartum period.

Physical Activity Energy Expenditure and Total Daily Energy Expenditure in Successful Weight Loss Maintainers

OBJECTIVE

The objective of this study was to compare physical activity energy expenditure (PAEE) and total daily energy expenditure (TDEE) in successful weight loss maintainers (WLM) with normal weight controls (NC) and controls with overweight/obesity (OC).

METHODS

Participants were recruited in three groups: WLM (n = 25, BMI 24.1 ± 2.3 kg/m² ; maintaining ≥ 13.6-kg weight loss for ≥ 1 year), NC (n = 27, BMI 23.0 ± 2.0 kg/m² ; similar to current BMI of WLM), and OC (n = 28, BMI 34.3 ± 4.8 kg/m² ; similar to pre-weight loss BMI of WLM). TDEE was measured using the doubly labeled water method. Resting energy expenditure (REE) was measured using indirect calorimetry. PAEE was calculated as (TDEE - [0.1 × TDEE] - REE).

RESULTS

PAEE in WLM (812 ± 268 kcal/d, mean ± SD) was significantly higher compared with that in both NC (621 ± 285 kcal/d, P < 0.01) and OC (637 ± 271 kcal/d, P = 0.02). As a result, TDEE in WLM (2,495 ± 366 kcal/d) was higher compared with that in NC (2,195 ± 521 kcal/d, P = 0.01) but was not significantly different from that in OC (2,573 ± 391 kcal/d).

CONCLUSIONS

The high levels of PAEE and TDEE observed in individuals maintaining a substantial weight loss (-26.2 ± 9.8 kg maintained for 9.0 ± 10.2 years) suggest that this group relies on high levels of energy expended in physical activity to remain in energy balance (and avoid weight regain) at a reduced body weight.