Mediterranean-Style Diets More Successful in Long Term Weight-Loss Programs than Low Fat Diets

Apr 19, 1999

Almost three times as many people were able to stick to a higher fat diet that included peanuts and peanut butter during an 18-month weight-loss study. Researchers at Harvard Medical School and Brigham and Women’s Hospital in Boston assigned 101 overweight men and women to either of two weight loss diets: 1) a low fat diet and 2) a higher monounsaturated-fat, “Mediterranean-style” diet. They found that subjects on the “Mediterranean-style” diet fared better throughout the study period. The high-fat group lost an average of 11 pounds each, while the low-fat group lost an average of six pounds each. In addition, over 80 percent of the subjects on the low-fat diet dropped out of the study compared to less than half (46%) of the subjects on the higher fat, “Mediterranean-style” diet. Study results were announced today at the Experimental Biology annual meeting in Washington, D.C.

The “Mediterranean-style” diet included foods high in heart-healthy monounsaturated fat such as peanuts, peanut butter, peanut oil, nuts, avocados and olive oil on a daily basis. When allowed to choose their own MUFA-rich foods, subjects consistently chose peanut butter (one serving per day), peanuts (1/2 serving per day), and mixed nuts (1/2 serving per day), favorite foods that used to be on a dieter’s “forbidden list.” Peanuts and peanut better helped to contribute to many important nutrients beyond “good fats,” including plant protein, vitamin E, fiber, folate, magnesium and hard-to-get nutrients such as copper, potassium and zinc. Each of the diets included many fruits, vegetables and grains and provided more than adequate levels of vitamins and minerals. Interestingly, those on the higher fat diet also ate more vegetables, fiber, and protein. This may be due to the fact that Mediterranean dishes typically consist of many vegetables and whole grains, sprinkled with peanuts and nuts or drizzled with peanut or olive oil to emphasize palatability.

These results are significant as the science community continues to investigate the question of the amount and type of fat in the diet for optimal health. It is clear from this study that for an overweight person, a 35% high-MUFA diet can lower BMI (body mass index), help maintain weight loss and even lower systolic blood pressure. Frank Sacks, associate professor of medicine at Harvard Medical School, is a co-investigator of the study and a leader in the fat debate. He notes, “Weight-loss studies that use low-fat diets have not been successful in the past in sustaining weight loss. Long term adherence with low-fat diets may be impeded by reduced satiety, palatability and variety.”

Kathy McManus, co-investigator and manager of clinical nutrition at Brigham and Women’s Hospital adds, “As obesity becomes an epidemic in America, it is more important than ever to identify eating patterns that can not only promote weight loss, but help sustain that weight loss for a lifetime. Patients were delighted to be able to eat peanuts and peanut butter again.” The Peanut Institute is a non-profit organization which supports nutrition research and develops educational programs to encourage healthful lifestyles.

The Peanut Institute is a non-profit organization that supports nutrition research and develops educational programs to encourage healthful lifestyles.