|First appearance||Mario & Luigi: Bowser's Inside Story (2009)|
|Latest appearance||Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey (2018)|
|Greater location||Bowser's body|
|Inhabitants||Tenderlings, Calorites, Kretins, Nutsoglobins, Princess Lipid|
The Flab Zone is an area in Bowser's body where Mario and Luigi go to find Princess Peach in Mario & Luigi: Bowser's Inside Story and its remake. This area can be explored only when Bowser is fat due to being tricked into eating excessive amounts of high-fat content food made by Fawful following Bowser's fight with Midbus. Here, Mario and Luigi encounter many new enemies. Through a few rooms, they find Peach being held by several Kretins. Mario and Luigi watch in horror as they carry her away. Luigi runs after, but he stops on a Donut Block and falls into mucus. A white figure named Princess Lipid drags Luigi up and gives the Mario Bros. badges. They proceed through several rooms with Save Blocks and blocks containing Attack Pieces, including vortex-like objects only to be used by a Spin Jump. After learning how to spin-jump and use the Jump Helmet, Mario and Luigi find the Kretins with Peach. Mario quickly brushes them off with his Spin Jump. Once the princess is conscious, however, the Kretins form together to make the Alpha Kretin. After the Kretins are defeated, Mario, Luigi, Peach, and Starlow proceed into two more rooms; in the second one, Peach is abducted by Fawful.
On their way, Mario and Luigi often encounter two pipes where only one is the right path; the other connects backwards, and if the two mistakenly enter it, they will lose their progress. Nutsoglobins are found in this area and provide information on which pipe the Mario Bros. should take.
Though the Flab Zone cannot be accessed while Bowser is skinny, the player can go back to this area whenever they desire once Bowser learns the body slam and has access to his castle. Bowser can return to the feast room and eat leftovers, though this time, he instantaneously gets fattened with one piece of food, allowing access to the Flab Zone again. When the player switches back to Bowser, he quickly exercises to get rid of the fat and move again.
The following are overworld items found in the Flab Zone in Mario & Luigi: Bowser's Inside Story.
|Super Mushroom||In a ? Block in the second scene.|
|In a ? Block in the upper scene after the first fork.|
|x2 In a ? Block in the first scene after the maze.|
|1-Up Mushroom||In a ? Block in the middle scene after the third fork.|
|Super Nut||In ? Blocks in the middle scene after the second fork.|
|Ultra Nut||In the secret room that can be accessed with the hidden blocks (see right)|
|Syrup Jar||In a ? Block in the lowermost scene after the second fork.|
|Supersyrup Jar||In a ? Block in the lower scene after the first fork.|
|In a ? Block in the uppermost scene after the third fork.|
|In a ? Block in the first scene after the maze.|
|Retry Clock||In a ? Block in the first scene.|
|Attack Piece||#1 In the attack piece block in the second scene.|
|#2–5 In a ? Block in the upper scene after the first fork.|
|#6–9 In a ? Block in the lowermost scene after the third fork.|
|#10 In an attack piece block in the scene with vomit.|
|EXP Socks||In the secret room that can be accessed with the hidden blocks (see right)|
|POW Boots||In ? Blocks in the middle scene after the second fork.|
|Good Badge||Given by Princess Lipid.|
|Mushroom Badge||Given by Princess Lipid.|
Names in other languages
|Possibly a shortening for "metabolism" + "space"|
|French (NOE)||Zone adipeuse||Adipose zone|
|Italian||Centro Metabolico||Metabolic Center|
|Spanish (NOA)||Depósito de Lípidos||Lipid Deposit|
|Spanish (NOE)||Sala Grasosa||Fat Room|
- abcd9146 (December 30, 2009). Mario & Luigi: Bowser's Inside Story FAQ/Walkthrough. GameFAQs. Retrieved June 10, 2016.