The crossword solutions for the term BMI RIVAL are OBESE (5 letters) and ELLE (4 letters). Body Mass Index (BMI) is a measure of body fat based on height and weight. It is used to determine whether someone is underweight, normal weight, overweight, or OBESE. OBESE is a term used to describe someone who is significantly overweight, while ELLE is a rival measure of body fat that takes into account age, gender, and muscle mass.