First of all, the nutrition facts given by USDA doesn't make sense to me. I'll refer only to skinless facts. Chicken breasts have 120kcal and chicken legs have the same. I know chicken breast have more protein and less fat, however I think chicken legs are much fattier.
I tried to calculate the amount of nutrients/calories in a chicken leg, but I got incongruent results.
I weighted full chicken headquarters without skin and it was 266g. I bake it in the oven at 400F/200C for 40 minutes and it reached and internal temperature of 200F/93C.
Cooked weight was 225g. Bones was 64g. Therefore: Raw meat: 266-64 = 202g ; 202g * 120kcal/100g = 242 kcal Cooked meat: 225-64 = 161g ; 161g * 174kcal/100g = 280 kcal So 280 kcal / 202g raw meat = 139 kcal / 100g raw meat
Why didn't they match? I think the are very well done, so they should have lost a lot of water. But they would have to lose more water so the calories match (In particular meat would have to weight 139g cooked).