Low-fat vs low-carb and Med-diet
On July 17, 2008, a study was published (1) that I believe should change how nutritionists and dietitians would look at the current Dietary Guide for Americans, the Food Guide Pyramid and the whole concept of a “heart-healthy” low-fat diet as recommended by the American Heart Association.
The paradigm-shift study was a 2-year intervention trial in The New England Journal of Medicine in which weight loss was compared among moderately obese subjects who were assigned to either a restricted-calorie Mediterranean diet, a non-restricted calorie low-carbohydrate, or a typical restricted-calorie low-fat diet (1). What did they find? Surprising results.
All the subjects lost weight, but were greater in both the low-carbohydrate group (despite nonrestricted calories) and the Mediterranean-diet group (1). The lipid profiles, more surprisingly, improved in the Mediterranean-diet group and most in the low-carbohydrate group (1). Best LDL cholesterol levels were found among the Mediterranean-diet group (1). The level of high-sensitivity C-reactive protein, most surprisingly, improved only in the Mediterranean-diet and low-carbohydrate groups (1).
The study, going further, took into consideration those with diabetes by measuring their fasting plasma glucose, insulin and glycated hemoglobin levels. There were no significant changes in fasting plasma glucose levels, but drastic decreasaes in insulin levels across the board (1). But the glycated hemoglobin decreased the most in the low-carb group (1).
Given the results of this study, my inclination is to adopt the Harvard School of Public Health’s Healthy Eating Pyramid because it appears to more resemble the Mediterranean-style of eating. And I would add recommendation for lower-carb eating in general along with inclusion of monounsaturated fat from olive oil and higher intake of fish versus red meat, etc.
1. Cheskin LJ, Kahan S. Low-carbohydrate and Mediterranean diets led to greater weight loss than a low-fat diet in moderately obese adults. Evid Based Med 2008;13:176.