People with obesity with similar [body mass index (BMI)](https://www.mcknights.com/news/stable-body-mass-index-helps-predict-better-cognitive-health-in-seniors-study/) measurements have differences in muscle and fat based on their age groups. This could mean that BMI isn’t the best tool for older adults, new research finds.
The research will be presented at this year’s European Congress on Obesity in Malaga, Spain, from May 11-14. People with obesity might have their fat and muscle redistributed as they age, without changes in their BMI, the authors said.
Teams from the University of Rome, University of Modena and Reggio Emilia in Italy and Beirut University in Lebanon evaluated 2,844 men and women with BMIs over 25. They broke participants into three groups by age: people who were 20 to 39 years old, people 40 to 59 years old, and people 60 to 79 years old.
Men had an increasing trend in total body fat percentage and decreasing lean mass as they aged, while women maintained similar values for those metrics at all ages. Men and women in the older groups had higher abdominal fat and lower muscle mass in arms and legs, despite the fact that all age groups in this study had similar BMIs.
“These results clearly indicate that we cannot rely only on BMI without considering the content and distribution of body composition in people with obesity across the different age groups,” Marwan El Ghoch, one of the researchers from the University of Modena, said in a [statement](https://www.news-medical.net/news/20250319/BMI-may-no-longer-be-enough-for-assessing-obesity-in-older-adults.aspx).
The redistribution could have some negative health impacts, leading to inflammation, insulin resistance and a higher risk for several cardiometabolic diseases, all without changes to BMI, El Ghoch noted.
The findings open up new pathways for future research as people with obesity might experience a redistribution within their fat and muscle as they age, without meaningful changes in their BMI. Namely, there’s an increased fat trunk accumulation and a decrease in muscle mass in the extremities, El Ghoch added.