Being overweight or obese is never good for one's health, but now a new study suggests it increases a woman's risk of broken bones.
For the study, researchers followed 20,000 women and men, aged 40 to 70, in the Canadian province of Quebec from 2009 until 2016. During a median follow-up of 5.8 years, 497 women and 323 men suffered a fracture.
There were 415 major osteoporotic fractures (hip, spine, wrist or leg), 260 in women and 155 in men. There were 353 leg fractures (ankle, foot, shin), 219 in women and 134 in men. There were 203 arm fractures (wrist, forearm or elbow), 141 in women and 62 in men.
Some fractures — such as wrist — were included in more than one category.
In women, a greater waist circumference (indicating more abdominal fat) was associated with an increased risk of a fracture. For each two-inch increase in waist circumference, the risk of a fracture at any site was 3% higher and the risk of a leg fracture was 7% higher. The association between waist circumference and ankle fractures was particularly strong, the investigators found.
In women, greater body mass index (BMI — an estimate of body fat based on weight and height) was associated with a greater risk of leg fractures.
For example, compared with women with a BMI of 25, those with a BMI of 27.5 had a 5% greater risk and those with a BMI of 40 had a 40% higher risk, while those with a BMI of 22.5 had a 5% lower risk.
It's not known why obesity is associated with a higher risk of fractures in women. However, most fractures are caused by falls, which are more common in obese people, according to the authors of the study presented at the European Congress on Obesity, held in the Netherlands from May 4 to 7.
"Waist circumference was more strongly associated with fractures in women than BMI. This may be due to visceral fat — fat that is very metabolically active and stored deep within the abdomen, wrapped around the organs — secreting compounds that adversely affect bone strength," said study author Dr. Anne-Frederique Turcotte, from the endocrinology and nephrology unit at CHU de Quebec Research Centre, in Quebec City.
"We also know that people with obesity take longer to stabilize their body, when they trip, for example," she said in a meeting news release. "This is particularly pronounced when weight is concentrated at the front of the body, suggesting that individuals with distribution of body fat in the abdominal area may be at higher risk of falling."
Among men, higher BMI and greater waist circumference were not significantly associated with fractures, but underweight men had two times the risk of arm fractures than those with normal weight.
"Our finding that obesity and, in particular, abdominal obesity, is linked to a higher risk of fractures in women has major public health implications," Turcotte said.
"We know that individuals with obesity who sustain a fracture are more likely to have other health problems that may cause slower rehabilitation, increase the risk of postoperative complications and malunion (fractures that may not heal properly), generating substantial health care costs," she added.
Study findings presented at meetings should be considered preliminary until published in a peer-reviewed journal.