The energy needed to raise the tempature.
Gut bacteria include Lactobacillus, the bacteria commonly used in probiotic foods such as yogurt, and E. coli bacteria. About a third of all bacteria in the gut are members of the Bacteroides species. Bacteroides are key in helping us digest plant food.
Well if you're referring to the human body, our cells make up a lot of everything we're made of. Muscles, organs, bones, blood, skin, etc. Biologically speaking, there's a lot to the human body besides organs. Sorry if this isn't very helpful.