I recommend LSD for fatties. Not to take every day or whatever, as with the other suggestions in this thread, but every now and then. It will kill your appetite for pretty much 8-12 hours straight, but that's not why I suggest it. It will make you look at yourself and other shit, ofc differently. It's also fun as shit.
With a lot of fatties, food is used as a coping mechanism for self-loathing, in this it is particularly useful as it will help you re-invent your self from the internal monologue up.
More facts: No physical addiction, cheap and readily available, nearly marijuana-levels of impossible to OD on and leaves your system for drug tests within 2-3 days.
Shrooms are also an alternative, and they can be even cheaper and easier to find, but they are also a little 'dirtier' of a trip and you may find less self-improvement if you get caught up in some /x/ tier nightmare world.