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

Abstract

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.

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

“…A recent study by Heinitz et al (79) reported the presence of adaptive thermogenesis during Phase 2 at weeks 1 and 3 with weight loss of about 100 kcal/d, the same average magnitude as observed by Muller et al (74). Martins et al (67) also observed an adaptive thermogenesis level of 90 ± 94.5 kcal/d ( P < 0.001) after 8 weeks of a 1,000 kcal/d low‐energy diet in participants with obesity. Adaptive thermogenesis was no longer significant (26.8 ± 121.5 kcal/d) following 4 weeks of weight stabilization during which the participants gained a small amount of weight.…”

“…This approach has the same effect as modifying the Harris‐Benedict equations by replacing Wt with adipose tissue and ATFM or fat mass and FFM. There are many published versions of these statistical REE prediction models that also include age, sex, and other covariates (67,68).…”

“…This approach has the same effect as modifying the Harris-Benedict equations by replacing Wt with adipose tissue and ATFM or fat mass and FFM. There are many published versions of these statistical REE prediction models that also include age, sex, and other covariates (67,68). Figure 3 Weight (Wt) gain following a period of positive energy balance includes not only an expanded adipose tissue compartment but also increases in the mass and structure of other tissues and organs, some of which are depicted in the figure.…”

“…Reaching a weight plateau (Phase 3) can take many months to arrive at a new steady state with neutral energy balance and fully remodeled organs and tissues (81). Of the available literature describing metabolic features of people reaching Phase 3, post-obesity, some conclude that predicted and measured REE are approximately equal, whereas others report persistent metabolic adaptations, even during periods of weight regain (25,46,67,68,(82)(83)(84)(85)(86)(87)(88)(89)(90)(91).…”

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

“…Moreover, in those with weight gain between week 9 and week 13, no metabolic adaptation was seen at week 13. Metabolic adaptation after WL was also not correlated with weight regain at the 1-year follow-up ( r = 0.034; P = 0.824; n = 45) ( 46 ). These 2 studies clearly show that metabolic adaptation at the level of RMR is minimal when measurements are taken under conditions of weight stability, and most likely not present under conditions of EB, and does not predict weight regain long term.…”