Imposed rate and extent of weight loss in obese men and adaptive changes in resting and total energy expenditure

Mario Siervo, Peter Faber, Jose Lara, Eileen R Gibney, Eric Milne, Patrick Ritz, Gerald E Lobley, Marinos Elia, R. James Stubbs, Alexandra M. Johnstone

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

OBJECTIVES: Weight loss (WL) is associated with a decrease in total and resting energy expenditure (EE). We aimed to investigate whether (1) diets with different rate and extent of WL determined different changes in total and resting EE and if (2) they influenced the level of adaptive thermogenesis, defined as the decline in total or resting EE not accounted by changes in body composition.

METHODS: Three groups of six, obese men participated in a total fast for 6days to achieve a 5% WL and a very low calorie (VLCD, 2.5MJ/day) for 3weeks or a low calorie (LCD, 5.2MJ/day) diet for 6weeks to achieve a 10% WL. A four-component model was used to measure body composition. Indirect calorimetry was used to measure resting EE. Total EE was measured by doubly labelled water (VLCD, LCD) and 24-hour whole-body calorimetry (fasting).

RESULTS: VLCD and LCD showed a similar degree of metabolic adaptation for total EE (VLCD=-6.2%; LCD=-6.8%). Metabolic adaptation for resting EE was greater in the LCD (-0.4MJ/day, -5.3%) compared to the VLCD (-0.1MJ/day, -1.4%) group. Resting EE did not decrease after short-term fasting and no evidence of adaptive thermogenesis (+0.4MJ/day) was found after 5% WL. The rate of WL was inversely associated with changes in resting EE (n=30, r=0.-42, p=0.01).

CONCLUSIONS: The rate of WL did not appear to influence the decline in total EE in obese men after 10% WL. Approximately 6% of this decline in total EE was explained by mechanisms of adaptive thermogenesis.

Original languageEnglish
Pages (from-to)896-904
Number of pages9
JournalMetabolism
Volume64
Issue number8
Early online date8 Apr 2015
DOIs
Publication statusPublished - Aug 2015

Keywords

  • obesity
  • weight loss
  • energy expenditure
  • metabolic adaptation

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