How Weight Affects Bone Breaks: A Global Study

A recent worldwide study dug into how body mass index (BMI) affects the chances of breaking bones. Researchers looked at data from over 1.6 million people across 32 countries, tracking them for about 16 million person-years.

Key Findings

• Underweight individuals have a higher risk of hip fractures in both men and women.
• Overweight or obese individuals initially appeared to have a lower risk of fractures.
• However, when bone mineral density (BMD) was factored in, the protective effect of being overweight or obese disappeared.
• In the most obese group (Obese II), the risk of fractures increased, especially in men.

Detailed Breakdown

The study split participants into different BMI groups:

• Underweight
• Normal weight
• Overweight

• Two levels of obesity (Obese I and Obese II)

• Underweight individuals remained at high risk for fractures even after adjusting for BMD, suggesting that low BMI is a strong risk factor for bone breaks, regardless of bone density.
• The increased risk in the highest BMI categories was more significant in men than in women.

Implications for Bone Health

These findings are crucial for updating the FRAX tool, which predicts fracture risk. The study highlights the complex relationship between weight and bone health, showing that it's not as straightforward as more weight equals fewer breaks.