Low-Fat Diet May Not Belly Up to Low-Carb and Mediterranean Diets

Author: Drucilla Dyess

While many Americans believe that the lower the fat in your diet, the better the results that will be achieved, a new study has found that a low-carbohydrate or Mediterranean-type diet may actually be more effective and just as safe.

Researchers from Brigham and Women's Hospital in Boston conducted a study of 322 moderately obese employees of a research center in Israel, 86 percent of whom were men, and found that the low-carb and Mediterranean diets were more effective that the low-fat diet in both weight loss and health benefits. The new study can be found in the New England Journal of Medicine.

Study participants were randomly assigning to three diet groups and were provided with encouragement and instruction over a two-year period. The three diet regimens included a low-carb diet, a low-fat diet and a Mediterranean diet. Those on the low-carb diet lost an average of 12 pounds in two years while those on the Mediterranean diet lost about 10 pounds. However, participants on the low-fat diet lost only 6.4 pounds after two years.

Researchers also found that those participants on the Mediterranean diet showed the most improvement in blood sugar levels, noting that this diet would provide the most health benefits for those at risk for diabetes, with the low carb diet being the best choice for people with cholesterol problems as it showed the most improvement in cholesterol levels. Both the low-carb and the Mediterranean diets promoted better cardiovascular health with the low-fat diet offering the least health benefits of any of the diets.

Dr. Meir Stampfer, co-chair of Brigham and Women's Hospital's Channing Laboratory, and lead study investigator said the study provides hard evidence that a low-fat diet is not necessarily the best diet. The main findings are that low-carb and Mediterranean diets are good (as long as the protein and fat sources are healthful), and even preferential diets for weight loss, as well as the fact that they are safe. Stampfer concludes, "The take-home message should be that we should abandon the idea that low fat diets are the number one way for people to lose weight - it wasn't the best diet. It can be helpful for some people, but overall I think the first choice should be the Mediterranean or the low carb."

Study participants met with dietitians periodically throughout the two years and usually ate lunch at the same cafeteria, where foods were color-coded with labels that corresponded to the diet type. The low-fat group participants were directed to eat low-fat grains, vegetables, fruits and legumes, and to avoid sweets. The low-carb group participants were advised to eat vegetarian sources of fat and protein and to limit intake of carbohydrates. It was recommended that the Mediterranean diet group eat a diet high in fish, poultry, olive oil and nuts. Calories were not limited for the low-carb diet, but for the two other diets, women were expected to eat a maximum of 1,500 calories daily with men consuming a maximum of 1,800 daily.

One of the great strengths of the study was that 95 percent of participants were still following the diet after one year, with 85 percent staying on it after 2 years which suggests that diets connected to the workplace may be particularly effective. Some businesses are now taking steps to write caloric limits or nutritional guidelines into their contracts with food service providers. Stampfer said "It'd be nice if employers institute this kind of thing more broadly. It's really in the employer's interest in having healthy employees and a modest investment in nutrition and support would benefit everyone."