Factors Contributing to Increased Risk of Obesity

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ FACTORS CONTRIBUTING TO INCREASED RISK OF OBESITY The laws of thermodynamics dictate that an energy surplus is at the root of all obesity; if energy intake (EI N) exceeds energy expenditure ( EO U T), then energy storage will occur. While this may seem obvious, it is important to state this at the outset. With all the recent attention devoted to claims about weight loss resulting from diets varying in macronutrient composition (e.g., high-carbohydrate diets, low-carbohydrate diets, high-protein/high-fat diets), one must not forget that diet composition will only affect long-term changes in body composition when there is an imbalance in EI N versus EO U T. Genetic vs Environmental Contributors Specific risk factors associated with increased weight gain in adults have been identified in some populations such as Caucasians and Pima Indians (Ravussin & Swinburn, 1993). An obvious risk factor is excess energy intake relative to expenditure, and the highly palatable, e n e rgy dense food supply in North America is undoubtedly a contributor to the high prevalence of obesity. Other identified risk factors include: 1) a low rate of resting energy expenditure relative to the rate predicted on the basis of body size; 2) high 24-h respiratory quotient (RQ), indicative of a higher 24-h carbohydrate oxidation and lower fat oxidation; and 3) low level of spontaneous physical activi t y. There are insufficient data available at this time to determine whether these risk factors for weight gain are characteristic of other population groups.