Obesity increases the risk of conditions such as cancer and diabetes
People who have obesity operations, such as gastric bypasses or banding, double their risk of suffering fractures, US research suggests.
Researchers for the Mayo Clinic in the US reviewed nearly 100 surgical cases spanning 21 years for their study.
They found a fifth of patients suffered fractures - twice the rate typical for their age - with most breaks occurring in the bones of the hands and feet.
The findings will be presented at the Endocrine Society Annual Meeting.
In the study, 21 individuals experienced 31 fractures within an average of seven years after their weight loss or bariatric surgery.
While most breaks were in the hands and feet, fractures of the hip, spine and upper arm bone - the humerus - were also reported.
Experts already know that there is extensive bone turnover and loss of bone density after bariatric surgery, but it was unclear whether that translated to fractures.
Lead author Dr Elizabeth Haglind said: "We've shown that risk of fractures after this type of weight-loss surgery is clinically significant.
"The results of our study show that patients who have had bariatric surgery have a two-fold risk in developing a fracture or sustaining a fracture as compared to the normal population."
She said more research was needed to confirm the findings and understand the specific risk factors and mechanisms involved.
Both obesity and weight-loss surgery are known to affect bone health.
Chronic vitamin D deficiency and inadequate calcium intake are common with obesity, and bariatric surgery poses a risk owing to malabsorption and decreased oral intake.
Dr David Haslam, of the National Obesity Forum, said although bariatric surgery might increase future fracture risk, this risk was likely to be far outweighed by the health benefits of the surgery in terms of reduction in weight and obesity-related conditions, such as cardiovascular disease and diabetes.
"For these reasons, the increase in risk is probably not worth worrying about. But we do need more study."