Amid the continuing confusion about whether the proportion of one macronutrient or another contributes to weight gain, a study published this month provides a welcome dose of clarity. Rather than measuring effectiveness of one diet or another, the research asks a question far more basic.

In "Carbohydrate Intake and Overweight and Obesity among Healthy Adults," published in the July issue of the Journal of the American Dietetic Association, researchers sought to determine, "If I am a healthy adult, is the likelihood that I will be overweight affected by the proportion of carbohydrates in my diet?"

The answer is a resounding yes.

The study of 4,451 Canadian subjects found that subjects who consumed the fewest carbohydrates were significantly more likely to be overweight than other participants in the study. Overweight and obesity prevalence was 65% in the lowest quartile of carbohydrate intake, 54% in quartile 2, 51% in quartile 3 and 51% in quartile 4.

Posing a challenge to those who vilify "bad carbohydrates," subjects in the quartiles 2 through 4 consumed more sugar and refined grains than those in the lowest quartile of carbohydrate intake. Most studies in recent years have approached the macronutrient question from another angle — which weight loss intervention is most effective? The problem with these studies has been compliance (getting subjects to rigorously follow diets has proven notoriously difficult) and the increasing conviction that diets simply don’t work.  The JADA study was not without limitations and certainly will not end the "carb debate," but the results create quite a high bar for those asserting that carbohydrates in isolation are making the public fat.