I know that Akimichi use technique where they expand their bodies and portions of their bodies by using Chakra. They can use calories as a source of energy which is why they're usually over weight and grow up learning to eat in large amounts as a normal thing. Akimichi can use pills to do the calorie to energy conversion for them but Choji has seen to use the technique without taking the pills. When doing calorie control a person grows wings of chakra like a butterfly and their fat goes away until the technique ends. Akimichi's expansion technique has been theorized to come from over use of chakra storage as well, for example when Naruto fought orochimaru he gathered a lot of chakra, condensed it and ate it, then his body expanded greatly from the chakra, madara in the recent chapters when kaguya started taking over, her chakra made madaras body expand, in the games and even a few episodes when choji does the human boulder he's seen with chakra radiating off of him, so it's theorized that the Akimichi clan may have a controlled use of this. However that's just a theory. That's pretty much everything I know about Akimichi.