How can i lose 20-40 lbs in a month without diets and pills?

Exercise: It's a simple math - you need to lose more calories than you take in. If you don't want to diet (that's the key though), then you need to lose calories and the only way i know of is to exercise and probably to exercise hard. Aerobic exercises is a must. Another way would be to do bariatric surgery. It does work, but i don't think it's easy to get done.