There isn’t one thing per say that could cure an eating disorder. Eating disorders are complex and can’t be treated overnight, they’d most likely require some sort of overtime approach to fully untangle the mental cords the illness brings.
But people with eating disorders usually end up going inpatient, or undergoing recovery through different methods (all in, reverse dieting, sticking to meal/calorie plans, etc), and usually continue that plan until weight restoration. Although this does change how they might look physically, these methods (especially if forced) unfortunately don’t work on fixing the disorder mentally (usually has to be done with a therapist, support group, family or on their own).