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

Background: Evidence in humans is equivocal in regards to whether resting energy expenditure (REE) decreases to a greater extent than predicted for the loss of body mass with weight loss, and whether this disproportionate decrease in REE persists with weight-loss maintenance. Objectives: We aimed to1) determine if a lower-than-predicted REE is present in a sample of successful weight-loss maintainers (WLMs) and 2) determine if amount of weight loss or duration of weight-loss maintenance are correlated with a lower-than-predicted REE in WLMs. Design: Participants (18-65 y old) were recruited in 3 groups: WLMs (maintaining ≥13.6 kg weight loss for ≥1 y, n = 34), normal-weight controls [NCs, body mass index (BMI; in kg/m2) similar to current BMI of WLMs, n = 35], and controls with overweight/obesity (OCs, BMI similar to pre-weight-loss maximum BMI of WLMs, n = 33). REE was measured (REEm) with indirect calorimetry. Predicted REE (REEp) was determined via 1) a best-fit linear regression developed with the use of REEm, age, sex, fat-free mass, and fat mass from our control groups and 2) three standard predictive equations. Results: REEm in WLMs was accurately predicted by equations developed from NCs and OCs (±1%) and by 3 standard predictive equations (±3%). In WLMs, individual differences between REEm and REEp ranged from -257 to +163 kcal/d. A lower REEm compared with REEp was correlated with amount of weight lost (r = 0.36, P < 0.05) but was not correlated with duration of weight-loss maintenance (r = 0.04, P = 0.81). Conclusions: We found no consistent evidence of a significantly lower REE than predicted in a sample of long-term WLMs based on predictive equations developed from NCs and OCs as well as 3 standard predictive equations. Results suggest that sustained weight loss may not always result in a substantial, disproportionately low REE. This trial was registered at clinicaltrials.gov as NCT03422380.

Estimating energy expenditure using heat flux measured at a single body site.

INTRODUCTION: The Personal Calorie Monitor (PCM) is a portable direct calorimeter that estimates energy expenditure (EE) from measured heat flux (i.e., the sum of conductive, convective, radiative, and evaporative heat). PURPOSE: The primary aim of this study was to compare EE estimated from measures of heat flux with those measured using indirect calorimetry in a thermoneutral environment (26°C). A secondary aim was to determine whether exposure to ambient temperature below thermoneutral condition (19°C) influences the accuracy of the PCM. METHODS: Thirty-four adults (mean ± SD: age, 28 ± 5 yr; body mass index, 22.9 ± 2.6 kg · m(-2)) were studied for 5 h in a whole-room indirect calorimeter (IC) in thermoneutral and cool conditions. Participants wore the PCM on their upper arm and completed two 20-min treadmill walking bouts (0% grade, 3 mph). The remaining time was spent sedentary (e.g., watching television, using a computer). RESULTS: In thermoneutral conditions, EE values (mean (95% confidence interval)) measured by IC and PCM were 560.0 (526.5-593.5) and 623.3 (535.5-711.1) kcal, respectively. In cool conditions, EE values measured by IC and PCM were 572.5 (540.9-604.0) and 745.5 (668.1-822.8) kcal, respectively. Under thermoneutral conditions, mean PCM minute-by-minute EE tracked closely with IC, resulting in a small nonsignificant bias (63 kcal (-5.8 to 132.4)). During cool conditions, mean PCM minute-by-minute EE did not track IC, resulting in a large bias (173.0 kcal (93.9-252.1)) (P <; 0.001). CONCLUSIONS: This study demonstrated the validity of using measured heat flux to estimate EE. However, accuracy may be impaired in cool conditions possibly because of excess heat loss from the exposed limbs.

Dietary habits and weight maintenance success in high versus low exercisers in the National Weight Control Registry.

BACKGROUND: The National Weight Control Registry (NWCR) was established to examine characteristics of successful weight loss maintainers. This study compares the diet and behavioral characteristics and weight regain trajectories of NWCR members with differing physical activity (PA) levels at baseline. METHODS: Participants (n = 3591) were divided into 4 levels of self-reported PA at registry entry (< 1000, 1000 to < 2250, 2250 to < 3500, and ≥ 3500 kcals/week). We compared self-reported energy intake (EI), macronutrient composition, eating behaviors (dietary restraint, hunger, and disinhibition), weight loss maintenance strategies, and 3 year weight regain between these 4 activity groups. RESULTS: Those with the highest PA at registry entry had lost the most weight, and reported lower fat intake, more dietary restraint, and greater reliance on several specific dietary strategies to maintain weight loss. Those in the lowest PA category maintained weight loss despite low levels of PA and without greater reliance on dietary strategies. There were no differences in odds of weight regain at year 3 between PA groups. CONCLUSIONS: These findings suggest that there is not a "one size fits all strategy" for successful weight loss maintenance and that weight loss maintenance may require the use of more strategies by some individuals than others.