Why are rhythmic gymnasts so skinny?

Answer 1

Many international rhythmic gymnasts are on very, verystrict diets. Another reason is like artistic gymnasts they train very hard from a young age which affects puberty and developement of the body. Artistic gymnasts build more solid muscle that gives them a little bit of bulk, while rhythmic gymnasts focus mostly on stretching and dance, so they don't have as much of the muscle mass that an artistic gymnast who trains for high impact skills would have or need. The ideal body for rhythmic gymnastics is slender and a little more long than for artistic gymnastics.

The reason why people think rhythmic gymnasts are all skinny is because that is all we see. Tiny twig athletes usually make the best rhythmic gymnasts, but not all are.