The Effect of a High-Fat Diet and Exercise on the Expression of Genetic Obesity1

In the United States, there are 300,000 obesity-related premature deaths each year. Further-more, no current obesity treatment program results in consistent weight reductions. Obesity is thought to be caused by complex genetic-environmental interactions. We studied the effect of two environmental factors, high-fat diet and non-weight-bearing exercise, on obesity expression. Young adult, female, genetically obese (fa/fa) rats (n = 52) and their lean (Fa/fa) littermates (n = 24) were studied using an experimental 2 × 2 × 2 factorial design (diet type, genetics, and exer-cise). Repeated measures ANOVA and secondarily stepwise regressions were used to analyze the data. The authors discovered that the effect of appetite on obesity expression is more limited than expected, and there may be critical stages when obesity expression is amenable to environmental modification. Almost 55 % of adults living in the Unites States were classified as over-weight as of 1998, with almost 23 % actually classified as obese by body mass index (BMI) (weight in kilograms divided by height in meters squared) greater than 25kg/m2 (Hill & Peters, 1998). More frightening still is the num-ber of U.S. children currently labeled as obese or overweight. The annual dol-lar costs of obesity are staggering; with the steady increase in obesity in this country between 1990 and 1998 combined with annual inflation, current costs can be estimated to exceed $100 billion (Hill & Peters, 1998). Further-more, these costs do not include hidden indirect expenses related to eating disorders and other less-obvious health and societal costs of obesity. For, despite years of traditional medical, surgical, pharmacological, and lifestyle change interventions (both diet and exercise), there are still more tha