Muscle Makes for Better Bones

Conventional medical wisdom has held that being overweight has one advantage: the extra weight puts enough stress on bones to help stimulate the formation of more bone tissue.  Overweight bones are typically stronger than those seen in thinner people who are believed to have a higher risk of osteoporosis.

But researchers in Belgium have challenged that view with a study showing that the fatter men in their study had smaller, thinner bones and that the size of their bones was affected most dramatically by the amount of fat in the trunk area. Of the 768 men between the ages of 25 and 45 whose bone density was examined, those with the largest, densest bones were those with the highest lean muscle mass. The researchers said that bone mass fell as the percentage of body fat rose and that bone mass increased as lean muscle mass rose. They concluded that bone mass is determined by "dynamic" loading provided by muscle mass rather than the "passive" loading from the weight of fat. The study was published in the July 2009 Journal of Clinical Endocrinology and Metabolism.