Weight is closely related to bone strength. In adults who are too fat, the bone density is high. If they are thin, the bone density is low. In fact, if we did not care about anything but the skeleton, we would want everybody to look like a Sumo wrestler! That is not healthy for the heart and the joints, so we don't advise everybody to become overweight. But it is important to avoid becoming too thin. Adults who lose weight lose bone density. Thin men and women are more likely to break bones when they are older.
It is a little more complicated in kids. Boys and girls who are too thin will definitely have lower bone density. If they are too heavy, sometimes the bone density will be high. But if kids are fat because they don't get any exercise, the bone density might be low and they might break their wrist more easily.
Some teenage girls have anorexia. They are too thin and don't eat enough food. This is really a serious problem and needs treatment by a doctor. The bones become very fragile and may never recover to normal strength.
The next section is about vitamin DUpdated 9/21/01