Canned foods are a particularly good way to lose weight, because portion, calories and carbohydrate control are locked in automatically. Most canned low carbohydrate vegetables (spinach, green beans, kale, collard greens, mushrooms, etc. – any veggie that comes in a can, except peas, potatoes or corn) are 50-100 calories per can. Most canned meats and fish (chicken, turkey, tuna, shrimp, lobster, crab, clams, sardines, mussels, Spam, Vienna sausage, etc) are 100-200 calories per small can. If you stick to just canned meats and canned low carbohydrate vegetables, you can eat 1-2 cans of each per meal, eat 2-3 meals a day, and probably lose about 5 pounds a week.