Earlier this week, I read a study that questioned the effects of 3 diets differing in macronutrient composition on energy expenditure during the maintenance phase after weight loss. The article can be found in JAMA, Ebbeling et al.
There were 21 overweight/obese adults that participated in this study.
- For 4 weeks they followed their usual diet while being monitored.
- After the 4 weeks, they went on a 12 week weight loss diet, approximately 60% of their usual diet, that resulted in ~2 pounds of weight loss a week. The average weight loss was 31 pounds. This diet included prepared calorie controlled meals.
- After the weight loss phase, they went on a weight stabilization phase that included prepared meals at the reduced number of calories needed to maintain their weight loss.
- The maintenance phase consisted of 12 weeks where the participants went on 3 different calorie controlled diets for 4 weeks each.
The 3 maintenance phase diets had the same number of calories, but the macronutrients varied. The diets were:
- A low carb diet that consisted of 10% calories from carbs, 30% calories from protein and 60% calories from fat. It was made up of mostly meat, chicken, fish, eggs, cheese, vegetables and fruit. It cut out potatoes, bread, sweets, pasta and starchy vegetables.
- A low glycemic index diet that consisted of 40% calories from carbs, 20% calories from protein and 40% calories from fat. It was made up of vegetables, fruit, beans, healthy fats and whole grains. It was similar to the Mediterranean diet.
- A low fat diet that consisted of 60% calories from carbs, 20% calories from protein and 20% calories from fat. It was made up of whole grains, fruits, vegetables and cut back on nuts, oils, fatty meats and other high fat foods.
During each of the phases, the participants energy expenditure, resting plus activity, was measured.
Before I get into the results, one effect weight loss has on the body is that the metabolism slows down. After weight loss, the body doesn’t need as much energy to function and maintain the weight as it did before dieting.
The results showed that the participants were able to lose weight and maintain weight loss by following a calorie controlled diet. The low carb diet had the least effect in slowing down the metabolism, the low glycemic diet had a moderate effect in slowing down the metabolism and the low fat diet had the greatest effect in slowing down the metabolism.
What this means is that people following a low carb diet would have an easier time maintaining weight loss than those following one of the two other diets. While this is great news, something to keep in mind is that a low carb diet appears to raise risk factors for cardiac disease and it is hard to maintain in the long run. It had the most beneficial effect on energy expenditure, but had a negative effect on physiological stress and chronic inflammation.
The effect of the low fat diet on energy expenditure would predict a regain of weight.
Out of the 3 diets, the one that is probably the best in the long run is the low glycemic diet. It didn’t slow down energy expenditure as much as the low fat diet and it didn’t raise risk factors for cardiac disease as the low carb diet. It is also easier to maintain over time.
Hunger rating did not differ between the 3 different diets.
- If you want to lose weight, eat less.
- Cut back on highly processed carbohydrates and sweets.
- Readjust you calorie intake to maintain weight loss.
- Don’t forget to exercise.
- Stay consistent.