In the ongoing battle royale between the hottest American trend diets, it seems one of them in particular always wins title of "most widely followed trend diet" — the standard low-fat diet.
The idea, it seems, has been that the lower in fat a diet is, the better its results. But this notion is one that is under fire from new research released today. And the study has already reignited a debate within the diet and nutrition community that could determine the eventual fate of the low-fat diet.
Researchers at Ben-Gurion University of the Negev in Israel found in a study of 322 obese subjects that the so-called Mediterranean diet — a diet plan characterized by high levels of healthy fats, fruits, and vegetables — beat out the low-fat diet both in terms of how much weight patients lost, as well as how many health benefits they gained as a result of the diet.
To determine this, researchers put study subjects on one of three diet regimens: a low-carb diet, a low-fat diet or a Mediterranean diet. Those on the low-carb diet lost the most weight in two years — about 12 pounds — while those on the Mediterranean diet lost about 10 pounds.
And in a finding that may surprise some, those on the low-fat diet lost the least weight — about seven pounds after two years.
Moreover, researchers found that a low-fat diet bestowed the least health benefits on the dieters compared with the Mediterranean and low-carb diets. Those on the Mediterranean diet were most likely to have improvements in blood sugar levels, while those on the low carb diet had the most improvement in cholesterol levels.
Lead study investigator Dr. Meir Stampfer, co-chair of Brigham and Women's Hospital's Channing Laboratory in Boston, Mass., said the study provides hard evidence that a low-fat diet is not necessarily the best diet.
"[The] main findings are that low-carb — as long as the protein and fat sources are healthful — and Mediterranean diets are good, and even preferential diets for weight loss, and they are safe," Stampfer said.
But some diet experts went so far as to say that the study provides further evidence that one of the biggest misconceptions about dieting is that dietary fat is anathema if you want to achieve the best results.
"The common misconception that low-carbohydrate, high-fat diets raise blood cholesterol is shown, again, not to be true," said Dr. Eric Westman, director of the Lifestyle Medicine Clinic at the Duke University Medical Center. "In fact, the diet with the highest amount of fat [the Mediterranean diet] lowered the total cholesterol/HDL ratio the most!"
Moreover, Dr. Paul Shekelle, director of the Southern California Evidence-Based Practice Center at the RAND Corporation, said that in his own experience he has found that the Mediterranean diet is the one that dieters are more likely to stick with for an extended period of time.
"The Mediterranean diet is the one I find patients are most likely to maintain long-term compliance with," Shekelle said, adding that the low-carb, high-protein diet commonly known as the "Atkins" diet is the one that dieters have the hardest time sticking to.
"If any primary care physician … has a patient on the Atkins diet two years on, you should probably find that patient and … find out how they did it," Shekelle explained. "I've not seen anyone in my practice who is still on the diet two years later. Compliance past a few months is the number one problem with the Atkins diet."