A lab-controlled study finds high-fat, low-carb diets to be effective in staving off weight loss. But how about in the real world?
As the co-author of a recent book called Why Calories Count: From Science to Politics, I am well aware of how difficult it is to lose weight.
- When you are dieting and losing weight, you require fewer calories to maintain and move your smaller body, and your metabolism and muscle activity -- and, therefore, your total energy expenditure-slow down.
- To maintain the weight loss, you need to eat less than you did before you began dieting.
But what would happen if you could adjust your diet to keep your energy expenditure from slowing down?
Enter Ebbeling et al in JAMA, with a comprehensive study to address precisely that question. The results of the study and editorial comments on the findings demonstrate how complicated and difficult it is to obtain definitive answers to questions about diet composition and calorie balance.
- The investigators asked whether calorie-controlled diets containing varying amounts of carbohydrate, fat, and protein, and varying in glycemic load (a measure of rapidly absorbable carbohydrates in foods) affected total energy expenditure in obese people who had just lost 10% to 15% of their weight, but were still obese.
- They found that the diet lowest in carbohydrate did not slow down energy expenditure as much as did the low-glycemic index diet, or the one lowest in fat.
- They concluded: "The results of our study challenge the notion that a calorie is a calorie from a metabolic perspective."