She and her friends join a new gym that promises instant weight loss. However, the gym is a front for Jadeite , who is using "Shape Rays" to drain energy from the girls.
If you are watching the more recent reboot, Sailor Moon Crystal , Act 4 is titled . Sailor Moon Episode 4
At the end of the episode, Usagi realizes that healthy habits are better than "quick fixes," though in the original Japanese version, she is dismayed to find she hasn't actually lost any weight. Episode 4 Summary (Sailor Moon Crystal) She and her friends join a new gym