I don't know if you will see this, but my daughters both have issues with weight. My 13 year old is morbidly obese and we have been trying for over two years to get her to lose weight. She has lost 7 lbs in the last 3 weeks because I am making her go to the gym with me and work out. We also had to restrict her diet, even when she would cry and say she was starving. She gets enough to eat, but she had stretched out her stomach over the years, so it was a matter of shrinking her stomach. Now, she doesn't overeat and she isn't stealing food anymore. She is ok with small portions too. She will never be skinny and that is ok. We are really hoping she will get down to about 130 ( she is 4'10" and 224 lbs right now)
I don't know if this helps, but if you would like to talk more, just drop me a line.