One of the major risk factors for osteoporosis is being too thin. Once the ovaries stop producing estrogen, a woman's body keeps on making small amounts of it from subcutaneous fat, especially abdominal fat. Therefore, a little extra weight is actually a good thing for menopausal women. Putting on this weight will help protect the bones, not just because of the continued natural estrogen production, but also because the strain of carrying the extra weight is a form of exercise and makes the bones work harder against gravity, thus helping to preserve bone density.
An extremely restricted diet after menopause that keeps the body as thin as that of a teenager could cause problems since weight loss is a known risk factor. According to the National Institute on Aging, women who lose 10 per cent or more of their body weight after the age of 50 have twice the risk of breaking a hip than women who don't lose weight (New York Times, June 4, 1996).