For decades, people have used the terms ectomorph, mesomorph, and endomorph to describe different body shapes. Ectomorphs are typically described as naturally lean, mesomorphs as more muscular and athletic, and endomorphs as having a broader build with a greater tendency to store body fat. These categories can sound convincing because many people recognize pieces of themselves in the descriptions.

There is even a popular wrist test that asks you to wrap your thumb and middle finger around the opposite wrist. If the fingers overlap, some claim you are an ectomorph; if they touch, a mesomorph; if they do not meet, an endomorph. It can be a fun way to think about frame size, but there is one important catch: this simple test cannot scientifically determine your metabolism, fitness potential, or ideal diet.