Does metabolism really change after weight loss? Leibel, Rosenbaum, Hirsch search for the answer.
Source: The New England Journal of Medicine – 1995, 332 (10), 621
Title: Changes in energy expenditure resulting from altered body weight
Authors: R. Leibel, M. Rosenbaum, J. Hirsch
This landmark study, with over 800 citations to date, reported a decreased resting metabolism (kCal/day) in 86% of the participants that underwent a calorie intake reduction to lose 10 or 20% of body weight. The study showed metabolism had slowed down following weight loss, leading to a reduced caloric intake for maintaining the new weight.
Conclusions: Losing or gaining weight is associated with compensatory changes in energy expenditure, which oppose the maintenance of the new body weight. These compensatory changes may account for the lack of success in long-term weight maintenance. Tracking metabolism is necessary to effectively manage caloric balance.
More details about the study: The individuals studied were ages 19-45, weighing between ~55 and ~155 kg, and followed a liquid diet to obtain a 10–20% plateau. The new weight was maintained for 14 days, after which resting metabolism was measured over the following 10 days. After a 10 percent gain in weight, the increase in total energy expenditure reflected a large increase in the absolute number of kilocalories of nonresting energy expenditure per day and a small increase in the absolute number of kilocalories per day attributed to the thermic effect of feeding. After a 10 or 20 percent loss in weight, the decline in total energy expenditure reflected similar decreases in both nonresting and resting energy expenditure. While the majority of participants (86%, n=25) showed a decreased resting metabolism (REE), the remaining participants (14%) either maintained REE (10%, n= 3) or increased REE (4%, n=1).