I had a gastroplasty done about 10 years ago. Why is it that on an average I consume no more than 800 calories, yet can't lose weight? I've had check ups and my thyroid glands seem to be working fine. I was on weight watchers and religiously followed their plan for 6 months and lost only 10 pounds. It's not hard to stick to a diet, only because you are stuffed after a small amount of food. What can I do to lose weight? I would like to lose 20 pounds.