One pound of body fat contains about 3,500 Calories, so if we're really overeating by 218 Calories per day, shouldn't we be gaining a pound of fat every sixteen days — twenty-three pounds per year — and requiring a forklift to get around after a decade or two? Actually, despite the popularity of this type of back-of-the-envelope math among popular media sources, public health authorities, doctors, and even some researchers, that's not how adiposity works. Hall and his colleagues have shown that this way of estimating changes in adiposity is way off target — and the consequences of this error have important implications for how we think about weight gain and weight loss.

One pound of body fat contains about 3,500 Calories, so if we're really overeating by 218 Calories per day, shouldn't we be gaining a pound of fat every sixteen days — twenty-three pounds per year — and requiring a forklift to get around after a decade or two? Actually, despite the popularity of this type of back-of-the-envelope math among popular media sources, public health authorities, doctors, and even some researchers, that's not how adiposity works. Hall and his colleagues have shown that this way of estimating changes in adiposity is way off target — and the consequences of this error have important implications for how we think about weight gain and weight loss.