Although I agree with nothing that Xenon has stated, lactose intolerance can be aided by the supplementation of lactase, the enzyme responsible for breaking up lactose, and would allow for the person to eat milk products safely
Xenon, I am sorry to say but the most reasonable way for someone to combat obesity would be to exercise and count the intake of calories, the burning of calories and create a deficit between the two numbers. The medical intervention should only be seen as a last resort because the existing procedures involved are too risky and cause problems with the absorption of needed materials.