Pretend you're broke. For most of us, this won't be a problem. But, if it is, just pretend you're me. Really broke. Budget $50 per week for groceries to feed four people - two grown men, one ravenous energizer bunny and yourself. This needs to be a very strict budget, it's best if you take fifty dollars in cash to the store and know if you go over the limit, you will be shockingly embarrassed.
In no time at all, you'll find yourself avoiding most snacks, the chips and candy aisle altogether, and practically all meat as well. This will do wonders for your waistline.