Patients often initiate commercial dietary plans to reduce obesity and prevent cardiovascular disease. Such plans include very low-carbohydrate, low-carbohydrate, very low-fat, and Mediterranean diets. Published evidence on several popular diets has made it easier for physicians to counsel patients about the health benefits and risks of such plans. Although the Atkins, Zone, Sugar Busters!, and South Beach diets have data proving that they are effective for weight loss and do not increase deleterious disease-oriented outcomes, they have little evidence of patient-oriented benefits. In contrast, the Mediterranean diet has extensive patient-oriented outcome data showing a significant risk reduction in mortality rates and in rates of fatal and nonfatal myocardial infarction. The American Heart Association released guidelines in 2006 that integrate recommendations from a variety of diets into a single plan. Physicians should emphasize diets that are rich in fruits, vegetables, and healthful fatty acids and that limit saturated fat intake. A stepwise individualized patient approach, with incorporation of one or two dietary interventions every three to six months, may be a practical way to help reduce a patient's cardiovascular disease risk.