I've always seemed to have trouble losing weight when eating bodybuilder level of protein. Was scanning PubMed on nitrogen balance and found this interesting study. These sedentary people had a weight maintenance diet of 40kcal/kg and were found to be in nitrogen balance. But they were only eating around 60 grams of protein which was the RDA.
http://ajcn.nutrition.org/content/49/6/1169.full.pdf
http://ajcn.nutrition.org/content/49/6/1169.full.pdf