Look into ketosis and ketogenic diet. That diet forces your body into burning fat without having to go hungry. There are pitfalls though that you need to know about, once a week you have a day where you eat carbs otherwise your body burns your collagen which can cause your hair to fall out and fingernails to snap. Proteins are also essential for building muscle and repairing your body after a workout. Fats are actually hard to get cheap in bulk, I'd recommend lots of eggs, it's a great cheap source of protein and it's filling. But do your research, don't take a randoms advice on a message board, look into it and do it properly