As the obesity epidemic persists, the time has come to end the pursuit of the “ideal” diet for weight loss and disease prevention. The dietary debate in the scientific community and reported in the media about the optimal macronutrient-focused weight loss diet sheds little light on the treatment of obesity and may mislead the public regarding proper weight management. Numerous randomized trials comparing diets differing in macronutrient compositions (eg, low-carbohydrate, low-fat, Mediterranean) have demonstrated differences in weight loss and metabolic risk factors that are small (ie, a mean difference of <1 kg) and inconsistent. In the past year alone, 4 meta-analyses of diet comparison studies have been published, each summarizing 13 to 24 trials.1-4 The only consistent finding among the trials is that adherence—the degree to which participants continued in the program or met program goals for diet and physical activity—was most strongly associated with weight loss and improvement in disease-related outcomes. The long history of trials showing very modest differences suggests that additional trials comparing diets varying in macronutrient content most likely will not produce findings that would significantly advance the science of obesity. Progress in obesity management will require greater understanding of the biological, behavioral, and environmental factors associated with adherence to lifestyle changes including both diet and physical activity.