BMI not the best guide
BMI measurements are inappropriate in older people and should be replaced by waist-hip ratios, say the researchers on a new study.
The London-based team found BMI overestimated risk of mortality from excess weight in those over 75 and might also underestimate the risks of low body weight.
Study leader Professor Astrid Fletcher, professor of epidemiology and ageing at the London School of Hygiene and Tropical Medicine, said: 'Our data make it very clear that waist-to-hip is very useful in the elderly.'
She added: 'People who have very low BMI are people who have lost both fat and muscle. They haven't had enough attention either.'
During follow up of 14,833 people aged 75 and over from 53 practices in the UK, 6,649 died. BMI was not associated with circulatory mortality in men and was negatively associated in women.
But after adjusting for BMI, waist-to-hip ratio did predict the risk of circulatory deaths. In men, the top quartile was at a 60 per cent greater risk than the bottom quartile, in women at a 56 per cent increased risk.