After realizing she's put on some weight, Truffles decides to go on a diet while dragging everyone else with her.

This episode features the following tropes:

• Beyond the Impossible: Flibber Flabber is designed as the perfect diet food—yet Chowder somehow manages to gain weight by devouring large portions of it. It's especially strange because Mung remarks that people have to eat a good deal of Flibber Flabber to drop pounds.
• Big Butt Blues: Truffles wants to lose weight due to her butt causing several buildings to fall on each other.
• Brown Bag Mask: Embarrassed when a hip check of hers knocks down a couple of buildings, Truffles dumps out her grocery bag, puts her mushroom hat on her rump, and then puts the bag on her head before flying off back to the kitchen.
• Brutal Honesty: When Truffles asks if she's become fat, Chowder wastes no time in confirming it. See Innocently Insensitive below.
• Comfort Food: Upset over realizing she's fat, she goes to cry herself to sleep, but not before having a snack with a stick of butter dipped with peanut butter.
• Crazy-Prepared: Chowder keeps an "emergency big-boy shirt" in a drawer for times when he rapidly gains weight from eating too much—which, given his Big Eater tendencies, happens quite often.
• Determinator: Even knowing that Flibber Flabber tastes bad and despite experiencing it first-hand, Truffles won't give up on the diet.
• Diet Episode: The central theme of the episode, though it ultimately doesn't follow how this trope is normally played out.
• "Eureka!" Moment: After Chowder eats too much Flibber Flabber, he puts on a bigger shirt to gain some relief. Mung realizes that larger items help a person feel smaller and gets the idea to secretly make their entire building bigger to make it look like Truffles lost weight.
• Failure Montage: Mung attempting to make Flibber Flabber more palatable.
• Here We Go Again!: After their plan to trick Truffles work, the boys spray the building with special water to shrink it back to normal size. Unfortunately, they shrink it too much to the point Truffles declares they're all going back on diets.
• Hope Spot: Mung thinks the crew dodged a bullet when Truffles merely goes to her room to cry herself to sleep after Chowder accidentally called her fat. Then she rushes back out and angrily blames Mung for it, and it snowballs into the titular diet.
• Innocently Insensitive: When Truffles has difficulty asking Mung if she's fat, not only does Chowder finish her sentence for her, but also confirms it rather bluntly, complete with Mung giving him a light thump on the head. Though it's fairly clear Chowder was only answering a question rather than trying to be mean-spirited.
  Mung: Chowder, Life Lesson #1: Never tell a woman she's fat!
• Instantly Proven Wrong: Mung brags that he, Schnitzel, and Chowder aren't fat...and then the camera zooms out to reveal that their clothes are struggling to contain their bodies.
• Jerkass Has a Point: While Truffles refuses to admit that she's also partly to blame for her weight gain by letting her terrible eating habits get to her, putting the sole blame on Mung and his cooking, and forcing everyone at the catering company to go on diets, she's not wrong to think they need to lose weight as well when she sees out of shape they are.
  Mung: Woman, you crazy! My cooking does not make anyone fat! The rest of us here are doing just fine! We are the picture of health!
  [camera zooms out to show Chowder, Mung, and Schnitzel severely overweight]
  Chowder: [breathes heavily] Bagel!
  Truffles: [stares flatly at the trio] ...I rest my case.
• Mood-Swinger: Truffles goes through a manic-depressive bout of mood swings in grief over her fatness.
  Truffles: (To a peanut butter jar she was snacking from) I hate you! I love you, I hate you! I love you. AAAAAAHHHH! (calmly) I'm gonna go cry myself to sleep.
• Never My Fault: While Truffles isn't wrong to think Mung's cooking is why she's gotten fat, she's only addressing half the problem. Truffles is just as guilty for letting her bad eating habits get the better of her (she ate an entire stick of butter dipped in peanut butter), but she's pinning the blame only on Mung and his food. The equivalence is an alcoholic blaming a beer company for their problem even though they're the ones who keep drinking.
• Only One Who Likes Spam: Flibber Flabber, the food that can help someone lose weight, is borderline inedible and impossible to cook properly. Yet for a reason that’s beyond Mung’s understanding, Chowder is the only person who likes it. Though considering this is Chowder, that's probably not much of a surprise.
• Parrot Expo-WHAT?: Mung asks Truffles how her trip getting groceries went.
  Truffles: (quickly) Oh it was fine. Yep, yeah, yes, just fine. EXCEPT FOR THE PART WHERE MY GIANT TUCHUS SMASHED THE CITY!
  Mung: Your what did who, now?
• Screw This, I'm Outta Here: Schnitzel attempts to invoke this trope after one too many failed attempts at trying to make Flibber Flabber more edible by trying to go on vacation for a month. Mung quickly shuts down the idea.
• Spit Take: The usual reaction to Flibber Flabber, complete with an entire of montage with Mung trying to make it more appealing and failing at every turn.
• Temporary Bulk Change:
  • In addition to Truffles feeling fatter than normal, Chowder, Mung, and Schnitzel are all shown to be bulging out of their clothes—just as Mung is bragging about how svelte they are. Seeing their chubbiness convinces Truffles to force everyone to join her in dieting.
  • Chowder, after devouring too much Flibber Flabber, bloats up into a ball and rushes to get his "emergency big-boy shirt" to feel more comfortable.
• This Is Gonna Suck: Truffles asking Mung for an honest opinion on whether she's fat or not causes Mung to push Chowder out of the scene with a grave "Chowder, take cover", before trying to non-answer his way out of the question.
• Vegetarian for a Day: In an attempt to lose weight, Truffles has everyone in the kitchen eat nothing but Flibber Flabber, a sort of dietary food that everyone hates. Everyone except Chowder.