These findings address a key question of whether regaining loss weight due to dieting is caused by metabolic or behavioral changes. The common belief is that the metabolic state after weight loss promotes weight regain. However, data germane to this supposition has been controversial and equivocal.
The failure to reach definitive conclusions in between these studies is linked to the way metabolic mass is estimated, the selection of research subjects, and the methods of weight loss and weight maintenance. Human studies are impractical, because there is no way to identify individuals predisposed to the development of obesity. Even if such identification was possible, it would be difficult to follow them throughout the protracted course of the development, treatment, and recurrence of their obese state.
Rats offer a better opportunity to address this issue. The ability to select obesity-prone rats, coupled with the shorter lifespan of the test animals and a better ability to control environmental conditions, offers researchers the opportunity to examine the metabolic state of an obese rat.
A New Study
This is the framework of a study performed through an assessment of indirect calorimetry, the balance of energy and fuel utilization in these obesity-prone rats throughout five stages of obesity development, treatment, and recurrence. Those stages are (1) pre-obesity; (2) established obesity; (3) weight-reduced; (4) weight-reduced after a period of weight maintenance; and (5) weight-re