A healthy weight can depend on many factors, including your age, sex, muscle mass, bone mass, and lifestyle. Some measures, like body mass index (BMI), do not take all of these measures into account.

This article was reviewed by Craig Primack, MD, FACP, FAAP, FOMA.We’ll start at the very beginning: Body mass index (BMI) is a measure of someone’s weight compared to their height whereas body fat ...