I am 42, and I was startled to be diagnosed with osteoporosis. I am very thin, having been a distance runner for years. I have frequently missed my period and been told this was because my body was stressed by my running. I thought exercise on top of good calcium intake was enough to make sure my bones stayed strong. What is the story?

Women who have frequent disruptions of their menstrual cycles, regardless of the cause (intense exercise, poor nutrition), may lose density in their bones, even though they exercise regularly. The longer the disruption, the worse the bone loss. Exercising to a certain point is good for the bones, but exercise taken to extremes is not. Talk with a qualified trainer or sports specialist to determine a safe running schedule.