Arakawa Under the Bridge (2010)

Season 2: Episode 10

With an apparent 500kg weight limit for the rocket to Venus, everyone goes on a diet so they can all go together. While Ric and the Mayor lose weight at a spa, the girls suffer through a strawberry only diet while the others have survival training with Sister. As a result of Sister's training, one of the Metal Brothers, Tetsuo, gains powerful muscles, and he soon confronts Stella to see who is more powerful. In order to stop their fighting, his brother Tetsuro builds up his muscles and manages to stop Tetsuo by showing a stronger love for his muscles.