HMM: Follicle-Stimulating Hormone as a cause of weight gain and bone loss in menopausal women.

It had long been assumed that the hormone’s role was limited to reproduction. F.S.H. stimulates the production of eggs in women and sperm in men.

Researchers knew that blood levels of F.S.H. soar as women’s ovaries start to fail before menopause. At the same time, women rapidly lose bone — even when blood levels of estrogen, which can preserve bone, remain steady.

Dr. Zaidi reasoned that F.S.H. could be a culprit in bone loss. So he and his colleagues created an antibody that blocked F.S.H. in female mice whose ovaries had been removed.

Since the mice were making no estrogen at all, they ought to have been losing bone. Indeed, the bone marrow in such mice usually fills with fat instead of developing bone cells. Much the same happens in women: That’s why their bones become less dense.

But in Dr. Zaidi’s lab, the mice that received the antibody did not developed fat-filled bone marrow — and, to his enormous surprise, they lost large amounts of fat.

Well, let’s hope this works out in humans.