You are what you don’t eat

Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. Sacks et al. N Engl J Med 2009;360:859-873

What is your favourite weight-loss diet? Low fat or high fat? Average protein or high protein? Low carb or high carb? Sacks and colleagues set out to answer these much debated questions in this large, long term, population-based trial and report that macronutrient composition made little difference. Although there were few drop-outs and treatment was intensive, the study was marred by a blurring of participants’ diets over time so in the end macronutrient differences between groups were less clear than originally envisaged. Nevertheless, they conclude that reduced-calorie diets result in clinically meaningful weight loss regardless of which macronutrients they emphasize. At the risk of stating the obvious, I think the chief take-home message is that a calorie is a calorie, regardless of whether it came from a KitKat or a celery stick: reduce your total calorie-intake and you lose weight. So, yes, you are what you don’t eat… in calories!