Congratulations on your weight loss. I understand your frustration with trying to maintain it without staying on a strict diet. Fortunately, there’s some good news: A new study from Boston’s Children’s Hospital suggests that a low-glycemic-index diet is the best strategy for keeping lost weight off. Here are the details:
The researchers noted that when you lose weight, your metabolism - the rate at which your body burns calories - slows down. That’s what makes it tough to maintain losses. The aim of this study was to find a diet that would enable you to continue to burn calories at the accelerated rate that was the norm when you started on the diet. The research team recruited 21 young adults who were overweight or obese and put them on diets so that they were able to lose between 10 to 15 percent of their body weight, about 30 pounds on average. Then they put their volunteers on one of three different diets that provided exactly the same number of calories but from different food sources. All of the volunteers spent four weeks on each of these three diets. One was a low-fat diet with 60 percent of calories from carbohydrate, 20 percent from fat and 20 percent from protein. The second was a low-glycemic-index diet designed to keep blood sugar stable. The version used in the study provided 40 percent of calories from carbohydrate, 40 percent from fat and 20 percent from protein. The third was a very low-carbohydrate diet with only 10 percent of calories from carbohydrate, 60 percent from fat and 30 percent from protein.
When the study began, the investigators measured each participant’s resting energy expenditure (calories burned while you’re inactive) and their total energy expenditure (calories burned during a typical day). After each of the four-week maintenance diets, the researchers measured everyone’s resting and total energy expenditures and compared these values with the measurements taken when the participants enrolled in the study.
They found that the low-fat diet slowed metabolism the most and that the low carbohydrate diet had a negative impact on certain hormone levels, resulting in increased inflammation in the body (and consequent increase in disease risk). The winner here was the low-glycemic index diet with its emphasis on fiber-rich, natural carbohydrates, proteins, and healthy fats, including nuts, avocados and olive oil.
These findings should help dieters who have lost weight and are having trouble keeping it off. You can eat very well when you emphasize foods that rank low on the glycemic index. In choosing carbohydrates, reduce your consumption of processed and refined foods (such as snack foods, sweetened drinks, sugary desserts, and products made with flour or sugar). Eat more sweet potatoes and fewer white potatoes, less bread (unless it's really chewy and grainy), more temperate fruits (especially berries, cherries, apples, and pears) and fewer tropical ones, and more beans. You could also try my anti-inflammatory diet that emphasizes the same low-glycemic index foods, gives you lots of variety and enough healthy carbs to satisfy.
Andrew Weil, M.D.