From Scientific American:
Some say the secret to losing weight is forgoing greasy, fatty foods like French fries; others swear that shunning carbs in favor of all-protein grub is key. Many popular weight loss plans recommend that dieters consume specific ratios of fat, protein and carbohydrates. (The Zone diet, for instance, prescribes 40 percent carbs, preferably complex carbs like veggies and whole grains, 30 percent protein and 30 percent fat). But a study published today in The New England Journal of Medicine suggests that the smartest way to lose weight is to eat heart healthy foods (think: Mediterranean diet—lots of veggies and fish, limited amounts of red meat) and reduce your caloric intake.
“Reduced calorie, heart-healthy diets can help you lose weight, regardless of the proportions of fat, protein and carbohydrates,” says study co-author Catherine Loria, a nutritional epidemiologist at the National Heart, Lung and Blood Institute in Bethesda, Md. The researchers, led by Frank Sacks, a professor of cardiovascular disease prevention at the Harvard School of Public Health in Boston, focused their study on 811 overweight and obese adults ages 30 to 70 in Boston and Baton Rouge, La. (“Overweight” includes those with a body mass index (BMI) between 25 and 29.9; people are considered obese if they have a BMI over 30. The BMI is a standard index used to gauge body fat based on a person's height and weight.)