Weight loss and weight gain is simple. It's calories in vs calories burned...we all know that. Sure, metabolism has some influence on that equation but every human still has a resting basal metabolic rate. Based on age and height/weight and activity level, it's a mathematical configuration that will tell you how many calories you need to maintain your current weight. If you eat more, you gain weight. I don't understand how a human being can eat at such a restrictive level, calorically speaking, and become morbidly obese. It's not that complicated and even if you had extremely poor metabolism, you still need at least 1,000 per day to pump blood through your heart and oxygenate your lungs, etc. Your situation is very interesting and suprising to learn about. Best of luck!