Should risk of bone fragility restrict weight control for other health reasons in postmenopausal women?--A ten year prospective study.

BACKGROUND

The aim of the present study was to investigate the health risks of excess body weight in the light of its protective effects on bone fragility.

METHODS

Femoral neck and lumbar spine dual X-ray absorptiometry was performed for 1970 Finnish women with a mean baseline age of 58.8 years (range 53.1-65.7 years) in 1994 and 2004. Women were categorized according to baseline BMI into normal <25 kg/m2, overweight 25-29.9 kg/m(2) and obese ≥30 kg/m(2). Weight change (kg) was categorized into tertiles. Co-morbidities, not allowed to be present at baseline, was based on self-reports. Osteoporosis was defined as femoral neck or spinal (L2-L4) T-score <-2.5 SD at 10-year follow-up or <-2.0 SD+low trauma energy follow-up fracture. Uni- and multivariate logistic regression models were used to estimate the 10-year risk of incident health disorders. Adjustment for age, number of diseases, alcohol intake and smoking was used in the multivariate models.

RESULTS

Obesity (Ob) and overweight (Ow) were related with higher 10-year risk of hypertension (OR=2.6 (Ob)/OR=1.7 (Ow), p<0.001), coronary artery disease (OR=1.6, p<0.05/OR=1.2, p=NS), diabetes (OR=11.7/OR=5.3, p<0.001), osteoarthritis (OR=1.4, p<0.05/OR=1.1, p=NS), chronic back pain (OR=1.6, p=0.007/OR=1.2, p=NS) and poor self-rated health (OR=2.4, p<0.05/OR=1.5, p=NS) and lower risk of osteoporosis (OR=0.13/OR=0.28, p<0.001). Weight change of less than +1 kg was associated 1.8 and 2.6 times lower 10-year risk of having hypertension and breast cancer than weight change over 6.2 kg. Among obese women the absolute risk increase of hypertension was 17%, of diabetes 12%, and absolute risk reduction of osteoporosis 14% in comparison to BMI <25 kg/m(2).

CONCLUSIONS

Health related risks of high BMI outweigh its protective effects on bone. Weight gain increases the risk hypertension and breast cancer.