After stepping out from a bath, Serena weighs herself and discovers that she has gained half a pound, and because of this, thinks she is fat, and begins skipping meals. Her family tells her otherwise. That night, Luna draws a picture of a fat Sailor Moon to mock her owner.

Jedite discovers the energy people use on fitness, and plans to use this to drain energy.

Melvin tells Serena, Molly, and two other girls that Miss Haruna is working out at a fitness program, and so they decide to go there. This fitness program has been taken over by Jedite, disguised as a man named Jed, whom the girls fall in love with. Serena leaves the exercises early, while Molly, Brandy, and the other girl finish and are taken to a room with relaxation pods, which really, once the girls are inside it, drain their energy.

Serena faints in Andrew's arms because she hasn't been eating, leading to a fantasy sequence where she dances with him and he tells her not to stop eating. He tells her the same thing her family told her: by fasting non-stop, she will do damage to herself. After she wakes up, Andrew says he wants to be a doctor, and takes Serena to a restaurant for dinner. When Serena is walking and eating donuts, she runs into Darien.

Serena returns to the fitness program after Luna tells her she is being irresponsible. Luna witnesses Jedite putting Miss Haruna in a "relaxation pod", and tells Serena that the Negaverse is behind this. After getting knocked down by Luna and threatened with a claw-scratching for disobedience, Serena transforms into Sailor Moon to stop Jedite, but he sends three bodybuilders (that he brainwashed with gold rings on their heads) after her. Sailor Moon destroys the rings on their heads with Moon Tiara Magic, releasing them from Jedite's control.

Afterward, Serena's younger brother, Sammy, plays a practical joke on Serena, tampering with the scale to make it read 300 pounds.