The latest study also shows that men’s total body fat increases compared to lean muscle mass as they age – but women appear to maintain the same ratio into later life
Scientists have identified how humans “redistribute” body mass from our arms and legs to our belly as we age.
A study of 2,844 people either overweight or obese also suggested men’s total body fat increases compared to their muscle mass as they age – but women maintain the same ratio into later life. The researchers at the University of Rome say the “redistribution” of body mass renders our body mass index (BMI) “useless and misleading” as we age because it may not necessarily increase. The research is published a day after the NHS was ordered to measure and record the BMI of tens of millions of Brits every year to flag whether they need help to lose weight.
Author Professor El Ghoch said: “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, since those in middle and older age have higher central adiposity and lower muscle mass.
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“The use of BMI becomes useless and misleading, and future research is needed to identify new tools that are able to detect these changes in fat and muscle mass in this specific population.”
The study included only people with a BMI of at least 25 and were split into three age groups; ‘young’ aged at 20-39 years, ‘middle-age’ at 40–59 years, and ‘older-age’ aged 60 to 79 years. One adult from each age group was matched by body weight and BMI.
Participants in the older age groups also had a higher “trunk fat percentage” and lower “appendicular lean mass” in their arms and legs. Men showed an increasing body fat percentage compared to lean muscle as they aged. The females maintained similar ratios of body fat to lean muscle across the age groups.
On Tuesday it was announced that everyone in England and Wales living with long-term conditions such as diabetes and heart disease should have their body mass index recorded annually on their medical record.
The National Institute for Health and Care Excellence (NICE) said an additional waist-to-height ratio measurement will be taken for people with a BMI below 35 – to flag those not carrying lots of extra weight but who are still out of shape. The draft guidance for the NHS is intended to help medics intervene with support to stop more serious or life-threatening conditions developing as a result of them being overweight or obese.
It does not provide a definitive list of long-term conditions but suggests medics focus on patients with COPD, diabetes, dyslipidaemia – abnormal levels of fats in the blood, heart failure, obstructive sleep apnoea, peripheral arterial disease, polycystic ovary syndrome, rheumatoid arthritis, schizophrenia, bipolar disorder, stroke or transient ischemic attack. It also advises anyone with a learning disability should also have their BMI taken annually.
Prof El Ghoch added: “Instead of BMI we need to rely on new simple-to-use tools that are able to detect these changes in fat mass and distribution – such as waist-to-height ratio – as well muscle mass and strength, including the handgrip test.
“Our findings suggest that people with obesity might experience a sort of redistribution within their body compartments of fat and muscle as they age, without meaningful changes in their BMI – namely an increased fat trunk accumulation and a decrease in muscle mass in the extremities.”
The findings are due to be presented at this year’s European Congress on Obesity in Malaga, Spain.