ABOUT TIME: New obesity definition sidelines BMI to focus on health. “The group’s revised definition, published in The Lancet Diabetes & Endocrinology1 on 14 January, focuses on how excess body fat, a measure called adiposity, affects the body, rather than relying only on body mass index (BMI), which links a person’s weight to their height. They propose two categories: preclinical obesity, when a person has extra body fat but their organs work normally, and clinical obesity, when excess fat harms the body’s organs and tissues.”