NEW YORK (Reuters Health) – In a 2-year study comparing different diets, low-carbohydrate and Mediterranean diets proved to be as safe and at least as effective as a low-fat diet in achieving weight loss.

The favorable effects of the low-carbohydrate diet on body fats and of the Mediterranean diet on blood sugar levels suggest that consideration of personal preferences and metabolic factors could be used to tailor a diet to the individual, Dr. Iris Shai and colleagues report in The New England Journal of Medicine.

The study was conducted with the assistance of a dietitian in a workplace setting in Israel between July 2005 and June 2007. The 322 study participants were 86 percent male, had an average age of 52 and most were obese. Forty-six subjects were diabetic and 118 had coronary heart disease.

The low-fat diet restricted calories to 1500 per day for women and 1800 per day for men, with up to 30 percent of calories obtained from fat.

The Mediterranean diet was rich in vegetables and low in red meat, with the same calorie restrictions as in the low-fat diet and up to 35 percent of calories from fat, including olive oil and about half a dozen nuts – less than 20 grams per day.

The low-carbohydrate diet did not restrict calories and allowed 20 grams of carbohydrates per day during the first 2 months and after holidays, increasing to a maximum of 120 grams per day.

“Although participants actually decreased their total daily calories consumed by a similar amount, net weight loss from the low-fat diet after 2 years was only 6.5 pounds (2.9 kg) compared to 10 pounds (4.4 kg) on the Mediterranean diet, and 10.3 pounds (4.7 kg) on the low-carbohydrate diet,” Shai from Ben-Gurion University of the Negev in Beer-Sheva told Reuters Health. “These weight reduction rates are comparable to results from physician-prescribed weight loss medications.”

The maximum weight reduction occurred within 6 months, followed by a partial rebound and then a plateau. Other health-related factors, including blood pressure, physical activity, and biomarkers for cardiovascular and liver disease continued to improve throughout the 2-year trial. “This suggests that a healthy diet has beneficial effects beyond weight loss,” Shai said.

The greatest improvements in lipid levels occurred with the low-carbohydrate diet, whereas the most favorable changes in fasting blood sugar and insulin levels among diabetics were associated with the Mediterranean diet.

“Clearly, one diet doesn’t fit all,” Shai noted.

To identify the diet that is likely to work best for individual patients, she recommends that, after describing the regimens, “physicians should ask questions regarding individual preferences (e.g., whether they have a hard time in counting calories and can try counting carbs), diet history (failures), and metabolic goals.”

“Whatever the choice is, the patient should stick with his or her own diet strategy and continue to be followed” by their health care provider or dietitian.

SOURCE: The New England Journal of Medicine, July 17, 2008.