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Repeat dieting may raise fracture risk in women

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Repeat dieting and weight loss are associated with an increased risk for nonvertebral fractures in women, a 15-year observational study indicates.

MedWire News: Repeat dieting and weight loss are associated with an increased risk for nonvertebral fractures in women, a 15-year observational study indicates.

The finding suggests that maintaining a stable weight could help protect against fractures, say Anne Søgaard (Norwegian Institute of Public Health, Oslo) and co-authors writing in Osteoporosis International.

Previous research has shown that women who repeatedly lose and then regain body weight are at increased risk for low bone mineral content, but ethical considerations preclude testing this in a prospective, randomized setting.

In the present study, Søgaard's team analyzed prospectively collected data to investigate whether intentional dieting was associated with subsequent fracture risk.

Their dataset was the Tromsø IV cohort, which included 20,745 people aged 25-69 years living in Tromsø, Norway, who were recruited in 1994-1995 and followed-up for approximately 12 years on average.

During follow-up there were 1339 nonvertebral osteoporotic fractures, three-quarters of which occurred in women. The mean age for fracture was 61.5 years in women and 58.3 years in men.

All participants completed questionnaires in which they stated whether or not they had deliberately tried to lose weight after the age of 19 years, and if so, approximately how many kilograms they had lost.

Among women, 4228 reported no weight loss, 2090 reported losing a maximum of 1-5 kg, 1856 reported losing 6-10 kg, and 996 reported losing 11 kg or more. Among men, the respective numbers were 6556, 1069, 921, and 516.

For both men and women, the highest body mass indices and bone mineral densities were observed in those with the largest amount of weight loss and the highest number of dieting episodes.

In addition, those who recalled no dieting episodes were most likely to be smokers, while those with the greatest weight loss were most likely to be inactive.

In adjusted analyses, women who had lost 6-10 kg or 11 kg or more had 1.3-fold and 1.5-fold increased risks, respectively, for nonvertebral osteoporotic fracture compared with women who reported no weight loss.

The association between weight loss and osteoporotic fracture was significant only in women aged 46 years and above at baseline, and in women who were of normal weight at baseline.

A similar pattern was seen for hip fractures in women, whereas no such associations were apparent in men.

Finally, there was a dose-response relationship between the number of dieting episodes and risk for osteoporotic fracture, such that women with 11 or more episodes had a 1.73-fold increased risk compared with women who had never dieted.

"The association between fractures and recalled dieting could be due to increased bone fragility, increased risk of falling or both, or it could be spurious," write Søgaard et al.

"Maintenance of a stable weight, which reduces the necessity and attempts of dieting, may have beneficial effects on fracture risk in women."

MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2012

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