Meta-analysis of Resting Metabolic Rate in Formerly Obese Subjects

Am J Clin Nutr. 1999 Jun;69(6):1117-22. doi: 10.1093/ajcn/69.6.1117.

Abstract

Background: A low resting metabolic rate (RMR) for a given body size and composition is partly genetically determined and has been suggested to be a risk factor for weight gain. Moreover, a low relative RMR has been reported in some, but not all, studies of formerly obese persons. The inconsistent reports may be due to a lack of statistical power to detect small differences in RMR and improper adjustment for body size and composition.

Objective: We conducted a meta-analysis based on published studies of RMR in formerly obese persons [body mass index (in kg/m2) < or = 27] and matched control subjects who had never been obese.

Design: We performed both an individual subject data meta-analysis and a traditional meta-analysis.

Results: The individual subject data meta-analysis included 124 formerly obese and 121 control subjects. RMR adjusted for differences in fat-free mass and fat mass was 2.9% lower in formerly obese subjects than in control subjects (P = 0.09). A low relative RMR (> 1 SD below the mean of the control group) was found in 3.3% of the control subjects and in 15.3% of the formerly obese subjects [difference: 12% (95% CI: 4.7%, 19.3%); P < 0.003]. The traditional meta-analysis was based on 12 studies (including 94 formerly obese and 99 control subjects) and included 3 studies not represented in the individual subject data analysis. In this analysis, relative RMR was lower in the formerly obese group than in the control group by 5.1% (95% CI: 1.7%, 8.6%).

Conclusions: Formerly obese subjects had a 3-5% lower mean relative RMR than control subjects; the difference could be explained by a low RMR being more frequent among the formerly obese subjects than among the control subjects. Whether the cause of the low RMR is genetic or acquired, the existence of a low RMR is likely to contribute to the high rate of weight regain in formerly obese persons.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Basal Metabolism / genetics*
  • Body Composition
  • Body Mass Index
  • Humans
  • Obesity / genetics
  • Obesity / metabolism*
  • Reference Values
  • Weight Loss / physiology*