The case for randomized clinical trials on the treatment of obesity

Some say that randomized clinical trials on weight loss are unnecessary ("the benefits are 'obvious'") and others say that such trials are not feasible because too few participants will succeed in maintaining weight loss. Although the intermediate term benefits of weight loss are beyond dispute (lowering of blood pressure, lipids, blood sugar, etc.), there is no proof that these benefits will translate into long term benefits, i.e., lower rates of cardiovascular disease and/or lower overall mortality. While this extrapolation may seem obvious, the clinical trials' literature is full of unexpected, adverse side effects of theoretically appealing therapies (e.g., higher mortality with clofibrate and higher cardiovascular disease rates with estrogen treatment in men). Although there is clearly a voluntary component to food ingestion, there are also powerful physiological forces at work which impact on energy balance. For example, individuals of similar height and weight may nevertheless have widely different daily energy expenditures and hence energy requirements. It has been shown in Pima Indians that those with low energy expenditure (i.e., those who are "fuel efficient") are more prone to future weight gain than those with high energy expenditure. Also, reduced obese individuals have lower 24-hour energy expenditure than individuals who are spontaneously at the same lean weight. It appears that this deficit in energy expenditure may last for several years, if not longer, implying that reduced obese individuals must exercise far greater vigilance over their caloric intake than their spontaneously lean peers.(ABSTRACT TRUNCATED AT 250 WORDS)