What is the influence of weight change on forearm bone mineral density in peri- and postmenopausal women? The Health Study of Nord-Trondelag, Norway

Weight loss in the elderly increases bone loss and the risk of fractures, especially at the hip and spine. The influence of weight change on non-weight-bearing parts of the skeleton is less well known. The purpose of this study was to investigate an association between weight change during the peri- and postmenopausal years and forearm bone mineral density (BMD). Among 8,856 women aged 45-60 years attending the first Health Study of Nord-Trondelag, Norway (HUNT I, 1984-1986), a random sample of 2,795 women was invited to forearm densitometry (single x-ray absorptiometry technology) at HUNT II (1995-1997), after a mean period of 11.3 years. A total of 2,005 women (mean age: 65.1 years) were eligible. The mean weight had increased 3.4 kg; the gain was greater in the youngest women. A total of 382 women (19.1%) had lost and 1,331 women (66.3%) had gained weight. Weight change explained little of the BMD variance, 0.7% and 0.4% for weight loss and weight gain, respectively. Weight loss was an independent and statistically significant negative predictor of BMD, adjusted for body weight, age, age at menopause, smoking, and ovarian hormone treatment, particularly among women with a baseline body mass index greater than 25 kg/m(2). No independent association between weight gain and forearm BMD was found.