A low-fat diet has been advocated as one of the best ways to lose weight for more than 40 years, and yet obesity rates continue to rise. The low-fat—and by extension, the low-calorie—diet fails to distinguish between fats, and fats are often replaced in diet foods and drinks by starches and sugars.
The low-fat approach also stops people from eating good fats, such as in nuts, fish and vegetable oils, all staples of the Mediterranean diet, say researchers from the University of Barcelona.
They tested two types of Mediterranean diet—one rich in nuts and the other high in olive oil—against a typical low-fat diet on a group of 7,447 people who were overweight or obese, and had type 2 diabetes. After five years, the fat intake in the low-fat group had fallen, and had risen in both the Mediterranean diet groups, and yet the greatest weight loss was seen in the latter two groups. The greatest increase in waist size was also among the low-fat group.
“We must abandon the myth that lower-fat, lower-calorie products lead to less weight gain. This illusion leads to paradoxical policies that focus on total calories, rather than food quality, a ban on whole milk but allow sugar-sweetened, fat-free milk”, said Prof Dariush Mozaffarian from Tufts University in an accompanying editorial.