Opinion

What if the focus on calories and energy balance is simply wrong?

David S. Ludwig is a co-director of the New Balance Foundation Obesity Prevention Center at Boston Children’s Hospital, professor of pediatrics at Harvard Medical School, and professor of nutrition at the Harvard T.H. Chan School of Public Health.

The usual way of understanding obesity is simple: If you consume more calories than you need to fuel yourself, the surplus is deposited into body fat, and you gain weight. Because, according to this approach, all calories are alike to the body, the only way to lose weight is to eat fewer of them or burn more off with exercise.