A Riot of Diets: What Works, What Doesn't

July 1, 2005
John Whyte, MD
John Whyte, MD

One third of all American adults (more than 70 million people) are currently on a diet. More than half of all adults have attempted dieting at some point--often more than once.

One third of all American adults (more than 70 million people) are currently on a diet. More than half of all adults have attempted dieting at some point--often more than once.1,2

In the Table, we compare 5 of the most popular diets. The goal is not to determine which diet is best but to understand what patients are consuming and help them develop an eating strategy that emphasizes important nutritional elements.


The results of a study that compared the Atkins, Ornish, Weight Watchers, and Zone diets was published earlier this year.3 It involved 160 patients ranging in age from 22 to 72 years; all patients had at least one risk factor for heart disease. Most of the patients were obese.

By the end of 1 year, all patients had lost weight--about 4% on average--and all the diets had produced a reduction in low-density lipoprotein cholesterol levels and an increase in high-density lipoprotein cholesterol levels. Moreover, all patients who had completed any of the diets showed some reduction in the risk of heart disease after 1 year. However, by 1 year, one third of the patients in the Weight Watchers and Zone programs had quit, and about half the patients enrolled in the Atkins and Ornish programs had quit. The specific diet did not matter as much as the ability to adhere to a nutritional plan.


Most diets recommend avoiding highly processed foods, reducing caffeine and alcohol consumption, using multivitamin/mineral supplementation, and increasing water intake; these are all good recommendations. However, diets typically exclude certain foods and therefore often cause nutritional deficiencies. For example, high-fat, low-carbohydrate diets are low in vitamin E, vitamin A, thiamin, folate, calcium, magnesium, and zinc. Low-fat diets are typically deficient in vitamin E and vitamin B12.

Because diets often involve avoidance of certain foods, patients typically do not follow them for long. As a result, there is little value in starting a diet that will probably be abandoned.

Advise patients to focus less on dieting and more on lifestyle changes that promote healthful eating. Modest weight loss of even 5% can result in significant health improvement.4


The issue is not low-carbohydrate versus low-fat; instead, healthful eating incorporates a spectrum of choices. It is as important to include--as it is to exclude--certain foods.

Reviewing and modifying diet is one of the most important steps in helping patients lose weight. Keep nutritional information simple. Remind patients that they need to eat food from all food groups so that their diet remains nutritionally adequate.

The key is moderation. Advise patients to monitor total daily calories; for most persons, an appropriate intake is about 2000 calories. The components of a healthful diet are listed in the Box.5 Dieting is not the solution to weight loss; rather, healthful eating is the key to successful weight management.




National Center for Chronic Disease and Health Promotion. Behavioral Risk Factor Surveillance System, 2003. Available at: http://www.cdc.gov/brfss/index.htm.


Jakicic JM. Exercise in the treatment of obesity.

Endocrinol Metab Clin North Am.



Dansinger ML, Gleason JA, Griffith JL, et al. Comparison of the Atkins, Ornish, Weight Watchers, and Zone diets for weight loss and heart disease risk reduction.




National Institutes of Health. Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults.

Obes Res

. 1998;6:51S-210S.


Dietary Guidelines for Americans, 2005. Available at: http://www.healthierus. gov/dietaryguidelines. Accessed June 24, 2005.