Resting energy expenditure in reduced-obese subjects in the National Weight Control Registry

Abstract

Background: Weight loss in obese subjects is associated with a reduction in resting metabolic rate (RMR). Whether the reduction can be explained solely by a reduction in lean body mass remains controversial. Objective: Our objective was to determine whether the reduction in RMR after weight loss was proportional to the decrease in lean mass alone or was greater than could be explained by body composition. Design: We measured the RMR, fasting respiratory quotient (RQ), and body composition in 40 reduced-obese subjects [ie, 7 men and 33 women who had lost ≥ 13.6 kg (30 lb) and maintained the loss for ≥ 1 y] enrolled in the National Weight Control Registry and 46 weight-matched control subjects (9 men, 37 women). Results: A stepwise multiple regression found lean mass, fat mass, age, and sex to be the best predictors of RMR in both groups. After adjusting RMR for these variables, we found no significant difference in RMR (5926 ± 106 and 6015 ± 104 kJ/d) between the 2 groups (P = 0.35). When we adjusted fasting RQ for percentage body fat and age, the reduced-obese group had a slightly higher (0.807 ± 0.006) RQ than the control group (0.791 ± 0.005, P = 0.05). This may have been due to the consumption of a diet lower in fat or to a reduced capacity for fat oxidation in the reduced-obese group. Conclusion: These results show that in at least some reducedobese individuals there does not seem to be a permanent obligatory reduction in RMR beyond the expected reduction for a reduced lean mass.Am J Clin Nutr 1999;69:1189-93.

Measured and predicted resting metabolic rate in Italian males and females, aged 18–59 y

“…Astrup et al (1999) showed that lower RMR values are usually found in (normal-weight) post-obese subjects compared to normalweight subjects and concludes that the obese state is at least partly the consequence of this lower metabolic rate. However, in a study of Wyatt et al (1999) no evidence was found that weight loss results in a lower than expected RMR, suggesting that many people will have a normal RMR after weight loss. It is well known that, although many obese individuals are able to lose weight, most cannot maintain the weight loss for longer periods.…”

Oxyntomodulin increases energy expenditure in addition to decreasing energy intake in overweight and obese humans: a randomised controlled trial

“…7 Increased sedentary behaviour is an important factor in the development of human obesity. 10 Whilst low-resting energy expenditure may contribute to obesity, 11,12 recent research has indicated it has minimal impact on weight gain 13,14 and activity-related energy expenditure may be much more important. 15 It has been reported that low physical activity accounted for 77% of weight gain over a year in one prospective study 16 and inactivity is a major determinant of increased adiposity during overfeeding.…”

Exercising the Obese Brain: Resetting the Defended Body Weight

“…However, high levels of exercise are reported by many obese individuals who successfully maintain long-term weight loss (26). Their success may be partly due to the fact that exercise prevents the reduction in metabolic rate, which usually accompanies chronic weight loss (27,28). Even so, this highly motivated group represents only a small percentage of the overall population of postobese individuals who are able to successfully maintain long-term weight loss.…”