Why can't I lose weight?

I've done so many things exercise and eating healthy and diets but they dont work there is nothing wrong with me. I do have scoliosis but that doesn't cause anything with me not losing weight etc.. Im 5ft 3 in and about 156 im unhealthy please help. My health is all i have left i just wnat to be healthy please help.
Why can't I lose weight?
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