Question

why do the bones of a overweight man crack very easily

Answer 1

This is because they start storing fats more than that of the useful proteins. In result, the excessive amounts of fats in the body regard bones from attaching to the muscles and also from getting calcium and other proteins. Thatswhy they become more fragile and hence can be broken easily.

Answer 2

Because overweighted person muscles get  loosen and  loosen muscles pressure on the bones get cracks in the bones.