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

Abstract

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.

FIGURE 1

Study CONSORT diagram. CONSORT, Consolidated Standards of Reporting Trials; REE, resting energy expenditure.

FIGURE 2

Individual variability in difference between REE_m and REE_p in WLMs. Bar chart of individual data for difference between REE_m and REE_p, predicted via the NCs-only equation in WLMs (n = 34). NC, normal-weight control; REE_m, measured resting energy expenditure; REE_p, predicted resting energy expenditure; WLM, weight-loss maintainer.

FIGURE 3

Correlation between adaptive thermogenesis and other factors in WLMs: (A) maximum weight, (B) maximum BMI, (C) maximum weight loss, (D) weight-loss duration. Scatter plot displaying results determined through the use of Pearson correlation to examine which factors were correlated with AT (calculated as REE_p – REE_m) in WLMs (n = 34), with REE_p predicted from NCs-only equation. A positive value on the x axis is indicative of AT. (A) Positive correlation between AT and maximum weight (i.e., those with a higher maximum weight exhibited a greater degree of AT). (B) Positive correlation between AT and maximum BMI (i.e., those with a higher maximum BMI exhibited a greater degree of AT). (C) Positive correlation between AT and maximum weight lost (i.e., those with greater weight loss exhibited a greater degree of AT). (D) No correlation between AT and duration of weight-loss maintenance. AT, adaptive thermogenesis; NC, normal-weight control; REE_m, measured resting energy expenditure; REE_p, predicted resting energy expenditure; WLM, weight-loss maintainer.