WEDNESDAY, July 16 (HealthDay News) -- New research shows that Mediterranean and low-carb diets are just as good and just as safe as the low-fat diet often prescribed by doctors, a revelation that should give people more choices in eating well.

"We can't rely on 'one diet fits all,' " said Iris Shai, an epidemiology researcher at Ben-Gurion University of the Negev in Beer-Sheva, Israel. "This suggests several diet strategies, and that we should be tailoring them."

Shai completed the study, which was published in the July 17 issue of the New England Journal of Medicine, while a Fulbright fellow at the Harvard School of Public Health and Channing Laboratory in Boston.

For this trial, 322 "moderately obese" men and women (but mostly men) were randomized to one of three diets: low-fat, restricted calorie; Mediterranean, restricted calorie; or low-carb, non-restricted-calorie.

The Mediterranean diet had the most amounts of dietary fiber and also included lots of fruits and vegetables. All three regimens had similar calorie counts.

Over the next two years, an astounding 84.6 percent of participants stayed on their diets.

Mean weight loss for the low-fat group was 2.9 kilograms (4.8 pounds), 4.4 kg (9.7 pounds) for the Mediterranean group and 4.7 kg (10.3 pounds) for the low-carb group.

For the 272 participants who stayed on their diets, the mean weight loss was 3.3 kg (7.3 pounds), 4.6 kg (10.1 pounds) and 5.5 kg (12.1 pounds), respectively.

The low-carb regimen reduced the ratio of total cholesterol to HDL "good" cholesterol by 20 percent, while the low-fat one lowered the ratio by 12 percent.

The best change in lipids was seen in the low-carb group, with a 20 percent increase in HDL cholesterol and a 14 percent decrease in triglycerides.

The Mediterranean diet produced the most favorable changes in blood glucose and insulin levels among the 36 participants with diabetes. In this group of patients, the low-fat diet increased fasting glucose levels.

According to the study authors, a low-carbohydrate, non-restricted-calorie diet may be optimal for those who will not follow a restricted-calorie dietary regimen. The increasing improvement in levels of some biomarkers up to the 24-month point, despite the achievement of maximum weight loss by six months, suggests that a diet with a healthful composition has benefits beyond weight reduction.

"The three diet strategies were beneficial for two years for all the biomarkers, but some of them were more specifically better than others," Shai said. "The good news is that you can consider and choose one strategy, but, once you choose one, you should stick with it."

"You have to look at each individual," added Lisa Harper Mallonee, a registered dietitian and an assistant professor of dental hygiene at the Texas A&M Health Science Center Baylor College of Dentistry. "Practice moderation and creating individual, healthy diets."

More information

The American Heart Association has more on the Mediterranean diet.