Sammendrag
Low body weight and weight loss has detrimental effects on bone. The purpose of this study was to investigate the effect on forearm bone mineral density (BMD) of weight change 11 years prior to, and during, a five years follow-up study in peri- and postmenopausal women.
In 1984-86, a total of 8,856 women aged 45-60 years, virtually all Caucasians, attended the first Nord-Trøndelag Health Study (HUNT I). Among these women, a random sample of 2,795 was invited to distal forearm densitometry (SXA technology) in 1995-97 (HUNT II), and 2,188 women (mean age: 65.1 years) attended. In 2001, 2,098 women were invited for subsequent forearm BMD, weight and height measurement and 1,421(67.8%) attended. After exclusion of women reporting hyper- or hypothyroidism or with missing weight data, a total of 1,302 women were eligible for analyses. Weight change was defined as a more than 1 kg increase or loss. The influence of weight change on BMD was assessed by linear and logistic regression and in general linear models, adjusting for body weight, smoking and oestrogen use at HUNT II.
During the 11.3 years between HUNT I and HUNT II, a total of 17.3% had lost and 68.8% had gained more than 1 kg. During the next 4.6 years, weight loss was observed in 40.1% and weight gain in 32.6% of the women. A total of 85 (6.5%) had lost and 284 (21.8%) had gained weight during both periods of observation. Mean annual loss in BMD was 1.03 %, highest in the youngest and oldest age groups. In linear regression models, with either prior or current weight change as independent variables, a statistically significant positive relationship between changes in weight and BMD was found. Women with previous weight loss experienced increased bone loss compared to women with previous weight gain, also when current body weight was stable or increasing. A significant reduction in bone loss was only seen in women who had gained more than 3.5 kg after a history of prior weight loss. In a logistic regression model with prior and current weight change (gain, stable and loss) as independent variables, the adjusted odds ratio (OR) for bone loss in the highest age-specific quartile (most bone loss) was 1.42 (p
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