Losing weight requires you to eat fewer calories than you burn. This calorie deficit can come from restricting calories, exercising to increase the number of calories you burn, or a combination of the two methods. Using a combination approach to weight loss allows you to lose weight without being overly restrictive with the foods that you eat. If you want to lose weight without exercising, you will need to cut calories more dramatically.
Determine how many calories you need to maintain your bodyweight. The University of Maryland Medical Center recommends that relatively inactive males multiply bodyweight by 13, and sedentary females multiply bodyweight by 10. The resulting number is the number of daily calories needed to maintain your weight.
Subtract from that number to lose weight. You need to burn 3,500 calories to lose 1 lb. If you don't plan to exercise, the entire deficit needs to come from cutting calories. Cutting roughly 500 calories a day from your target number will result in a 1-lb. weight loss each week. You can cut more dramatically to lose weight faster, but keep in mind that the stricter your diet, the more difficult it can be to maintain.
Maintain a food diary. Use a notebook, online diary or smartphone app to keep track of the number of calories you eat. Regardless of the method you use, a food diary is most effective when you track every bite you eat, including snacks and samples you eat during food preparation. A food diary also helps you notice whether you have a tendency to overeat at certain times of the day, allowing you to change bad habits.