Timmy wishes that everyone ate nothing but dessert, which at first leads to rushes in energy. Over time though, everyone becomes overweight, which Timmy sees as a partly good thing: No one is made fun of for being fat, and Francis tries to pick on thin kids (Mark Chang) but is too fat to even move! But the huge increase in weight is causing the Earth to crash into the Sun!
When Timmy doesn't want to eat his spinach, he throws it away and is vaporized by Cosmo & Wanda and then when he asks for dessert, his mom gives him carrot cake without the cake. Then Timmy tries A.J.'s house but finds out that he must multiply fractions for dessert and then at Mark Chang's place, where he had ice cream but it has vegetables. After that, Timmy wishes for no breakfast, lunch, or dinner, just desserts. Then Wanda explains that eating healthy gives one the energy. Timmy then started saying chocolate in his sentences, next, Wanda goes crazy and told Timmy to make the wish. Cosmo said he is not usually the sceptical one, and tries to explain what happens to Wanda eats a lot of sugar, as Wanda puts him in a bubble before he could say what happens, so Timmy makes the wish. The next morning his mom called him and gave him a cake and 3 bars of chocolate and a bowl of frosting. At school everybody is eating desserts and school is only 3 minutes and everything is in the rush, the sugar rush hour, and other things. Later Cosmo explains what will happen if Wanda eats to many sugars and explains what would happen to Dimmsdale but does not know. 28 days later, everybody was fat except for Mark Chang since Yugopotamia's dessert are healthy foods and everybody can't walk and has to roll. Francis tries to stuff Mark Chang into a locker, but he doesn't have any energy to bully anyone anymore. In Mr. Crocker's room he explains what would happen if Dimmsdale gets too heavy: the Earth hurtles into the sun. They eat more desserts, everyone in the class gets heavier, Trixie breaks through her belt and her belly drops over her tight skirt. The large bellies caused the chairs sink to the floor and then Dimmsdale went to the bottom, causing the Earth to start hurtling into the sun with a molten date with death (as stated by Sanhay) and then everybody in the room escapes. Timmy rolled back to his house but cannot reach the top, so he brought Cosmo and Wanda down. He tries to wish everything back to normal but Wanda does not have enough energy to lift her arms out. Timmy went to Mark Chang's spaceship and tries to get his last can of spinach cobbler. At first, Mark Chang declines, but after Timmy sits on him, he lets him have the can of spinach cobbler, and Mark Chang drops Timmy off at his house by using his ship. When Timmy gets back, he gives Wanda the spinach and now Wanda can lift her arms! Timmy makes the wish and POOF! everything is back to normal! Timmy learns his lesson of eating healthy food, but Cosmo still has his extra weight. Wanda then is revealed to be stuck somewhere in Cosmo, so he tries to retrieve her out of him, but finds only a cowboy hunting another cowboy called Billy the Goat.
Timmy's Mom also would've appeared as the main character in the episode, bouncing around like the Homer Ball from The Simpsons.
Edit
