title: Metabolic differences and the development of obesity.
abstract: Studies, such as those on Pima Indians, have shown that metabolic factors are involved in the development of obesity and that being overweight is not simply a result of "sloth and gluttony." However, the environment also affects the development of obesity. Among individuals in a given environment, the variability in body size is influenced by genetically determined responses to that environment. People with a low metabolic rate (adjusted for body size and composition) are prone to weight gain, whereas those with a high level of spontaneous physical activity are less likely to become obese. Similarly, individuals with a high 24-hour respiratory quotient (RQ) are more likely to gain weight than those with a low RQ. Insulin sensitivity (not insulin resistance) is another metabolic predictor of obesity. Genetic linkage studies suggest a number of genes are linked to the development of obesity. By sibling-pair linkage analysis, tumor necrosis factor-alpha (TNF-alpha) was found to be linked to the percentage of body fat, and other studies have shown that fat cell production of TNF-alpha is greater in obese individuals.
authors.affiliation: Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Phoenix, AZ 85016, USA.
authors.forename: E
authors.initials: E
authors.lastname: Ravussin
mesh_terms: D001130:Arizona / Q000453:epidemiology; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000208:ethnology; D004777:Environment; D005796:Genes / Q000235:genetics; D006801:Humans; D007198:Indians, North American; D007333:Insulin Resistance; D009765:Obesity / Q000209:etiology / Q000235:genetics / Q000378:metabolism*; D015430:Weight Gain