Data collection and analysis is the key to self-awareness, and self-awareness is the key to self-improvement. If you want to improve yourself, you need hard data on where you are and what is keeping you there. If you want to make better spending habits, you need to track every cent you spend so that it stares you right in the face. If you want to make better eating habits, you need a solid record of everything that goes into your mouth. The best tools to do this will vary from person to person, but for eating, I suggest the following: take a picture of everything you eat. Collect them by date and keep them somewhere that's always in front of you. You might be surprised how many biscuits, chocolates, coffees, snacks and fast food meals show up in what you think of as a healthy diet. Your mind is bad at seeing that pattern until it is forced on you. That's the point. Actual data is much more convincing than "I think I eat pretty healthy" or "I don't spend that much".
Mokalus of Borg
PS - Every fad diet works for someone, because they all start with "write down everything you eat".
PPS - Just like every weird budget technique works on some level by tracking what you spend.