GravesLady - Actually it's 66% of US population that is overweight, not the world -- but still a common problem. Otherwise, good comments.
Would test thyroid, but it's not the likely culprit.
You say you've had all the medical tests. Have you gotten TSH, FREE T3, and FREE T4? If so, please post your results (with normal bands). If not, get them.
This probably should go to the diet forum - but here is my 2 cents.
I am 29 lbs heavier than I would like to be and I am Hyper/Graves'. The 29 lbs is really ridiculous and unrealistic, whereas 17 lbs would be more realistically correct for my height, and an easier goal to achieve.
When weight has a genetic predisposition it makes it even rougher to lose and maintain our goal weight, so we have to work at it just a little harder than most. Maybe you are not on the right diet for your system, and the only way to find the correct diet is by trial and error. I also found that alternating 3 different diets helps as well because our system becomes lazy and weight lose at a plateau when on the same diet for too long. High protein, low glycemic vegetables and fruits worked for me. Meat, fish, foul and dairy when I wasn't a vegetarian years ago. These proteins have Tyrosine an amino acid which aids in the production of the adrenal, thyroid, and pituitary glands. Vitamin B6, folic acid, and copper are necessary for conversion of tyrosine into neurotransmitters. But watch the cholesterol!
Weight is a big issue thyroid or not - 66 % of the world's population is overweight.
Happy Dieting!
GL - Graves' Patient.