We had serious issues with Mollys weight, whatever commercial food I fed her, the weight would not shift. I took her to see Nick Thompson in Bath who specialises in Nutrition and has a more Hollisitic approach to things, not that I am saying Hollisitic works for everything, I appreciate it is taking a balanced view but it has a place.
We had an incident where Molly devoured a wing in one, fortunately it came straight back up. We changed to thighs and chopped them so we give them a mixture of the wing tips chopped up and the thighs plus a variety of fish. Molly also has the Higher Nature Ultimate Nutrition which contains 47 True Food Vitamins and claims to be a good quality product. As soon as we put Molly on any kind of commercial food, her weight balloons very quickly (we weigh it out carefully). We have big issues with Mollys joint and sm problems, I am paranoid about keeping her lean to the point we weigh her everyday
I am also very careful where I get the chicken from, I only buy from locals farms. I buy Neem sticks and get big bones from the farm for them to chew on as well.