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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. (Am Fam Physician. 2009;79(7):571-578. Copyright © 2009 American Academy of Family Physicians.)
Increases in obesity rates and in the prevalence of obesity-related illness have made dietary counseling an integral part of medical care.1 Patients often use commercial dietary plans to reach their weight-loss goals. Although some of these diets make unfounded claims, many of the more publicized plans have been studied in randomized, controlled settings. Focused counseling on the risks and benefits of these diets may be beneficial in helping patients reach their goals.
Many commercial diets can be subdivided into four categories based on the combinations of macronutrients recommended: very low-carbohydrate, low-carbohydrate, very low-fat, and Mediterranean diets (Table 1).2-32 The more restrictive diets include very low-carbohydrate, low-carbohydrate, and very low-fat diets. These plans modify the typical macronutrient ratios by increasing or decreasing the intake of dietary fat, carbohydrate, and protein. Less restrictive diets, such as the Mediterranean diet and American Heart Association (AHA) dietary guidelines,32 aim to increase the intake of beneficial fatty acids, fiber, fruits, and fresh vegetables.
A useful approach to analyzing these diets includes an evaluation of the evidence for weight loss, disease-oriented outcomes, and patient-oriented outcomes.
Very Low-Carbohydrate Diets