With the increased popularity of low-carbohydrate diets, Hays et al1 give an interesting perspective on the role of carbohydrate in weight loss. Although alluded to in the "Methods" section, it is impossible to believe that during the study, mean caloric intake increased by 1000 kcal/d in control subjects without these subjects gaining weight.2 The control groups' poststudy caloric intake most likely represents what both the control and high-carbohydrate diet groups usually ate prior to the study. Using this assumption, there is a mean nonsignificant deficit of more than 500 kcal/d between high-carbohydrate and control group individuals. Weekly, this becomes a 3500-kcal deficit, which is approximately the deficit needed to metabolize a pound of fat.2 Tied into this is the assumption that ad libitum is limited to 150% of estimated intake when usual intake for these subjects might be 200% of estimated intake.
Seshadri P. A Calorie by Any Name Is Still a Calorie. Arch Intern Med. 2004;164(15):1702-1703. doi:10.1001/archinte.164.15.1702-b