According to background information in the article, previous peer-reviewed study shows that successful dieters maintaining a 30 pound or greater weight loss usually follow their own individualized, primarily lower fat diet, not popular, low carb or commercial diets.

John La Puma, M.D., from the Santa Barbara Institute for Medical Nutrition and Healthy Weight and colleagues studied data from 394 practicing physicians. About half (196 or 49%) had not recommended any diet to their patients in the past 5 years. Almost half of the physicians—44 percent (174)-- were overweight or obese. More of the overweight physicians (94, 54 percent) recommended a popular diet than did healthy weight physicians (106, 48 percent). Physicians who did recommend diets most often recommended Weight Watchers (37 percent, 148 recommendations), followed by Jenny Craig (13 percent, 52 recommendations), and Atkins (12 percent, 47 recommendations).

The study also found that 72 percent (126/174) of overweight physicians had not followed a diet themselves in 5 years. Of those who had, however, 9 percent had followed low carb and 9 percent had followed low fat diets.

Dr. La Puma commented, "It's not enough for a few doctors to specialize in nutrition. A few words of encouragement about weight loss from any physician can be incredibly helpful to his or her patients."

The authors write, “Physicians seldom prescribe diets, though when they do, there is discordance between their personal use of and patient recommendation for popular diets. Physicians can and should begin to prescribe particular eating plans for their patients.”
http://www.nature.com/cgi-taf/DynaPage.taf?file=/ijo/journal/vaop/ncurrent/abs/0802840a.html&_UserReference=0A01016546B8631D89A570E4F4AF41953DAC
http://www.drjohnlapuma.com