Is Obesity Due to Overeating and Inactivity, or to a Defective Metabolic Rate? A Review

Abstract

Abstract The cause of obesity could be overeating and inactivity, a defective metabolic rate, or a combination of these factors. This article investigates the causes of obesity by reviewing studies which have examined food intake, physical activity, basal metabolic rate (BMR), and thermogenesis in relation to obesity. Energy intake is at best weakly related to obesity. Fat intake may be a more important factor in the etiology of obesity. Post- and pre-obese individuals seem to have lower weight maintenance energy requirements than “normal.” Physical activity may be a function of obesity level with lower levels of activity in the highly obese. BMR is reduced in the post-obese and is suggestive of a predisposing factor for weight gain. Thermogenesis may be blunted in a significant number of obese individuals.