Paleo seems to be popular around here but I am pretty skeptical of it actually being a good idea (I am open to updating if evidence is presented). Intermittent fasting is the only thing I really feel like I can recommend, and even that is something that will work for some people but not others (did not work for me, but LeanGains makes specific enough predictions that a sufficiently large number of people seem satisfied by that I am convinced it is a real phenomenon).

Also fixing any deficiencies you have (more water if you are dehydrated, for instance; probably more protein if you are a vegetarian).