The studies measured the participants' body mass index (BMI), a ratio of their heightandweight, but it wasn't able to take into account their body fat composition, or how much of their overall bodyweight was made up of fat versus muscle.
All models were required to have a body mass index -- a ratio of heightandweight -- above 18, the minimum limit considered healthy by the World Health Organization.
Body Mass Index (BMI) is defined as the ratio of weight (in kg) to height (in meters) squared and is an inexact measure of body fat, though it supposedly establishes cutoff points of normal weight, overweight, and obesity.