Overweight: waist / hip , best indicator of mortality than BMI in the elderly compared

Around waist / hip ratio is a better predictor of mortality risk associated with overweight and / or obesity in the elderly than the body mass index (BMI) , according to a study published in the "American Journal of Clinical Association ."
If attention is paid to the growing problem of obesity in the general population , the relationship between obesity and mortality is much less known in the elderly , say the authors .

While it is known that the risks associated with a high BMI ( weight ratio of the square of the height , the value of which reveals a situation of overweight ) decreases with age , the World Health Organization ( WHO) and the U.S. national Institutes of Health continue to use this tool with the same threshold values for the other age groups .

However, according to the study conducted by a team from the London School of Hygiene & Tropical Medicine in London, involving nearly 15,000 people over 75 years , the risk of excess weight are determined by BMI overestimated in this age group and even show inappropriate for older .

For example, a BMI between 25 to 27, indicative of overweight adults , is not a risk factor for mortality ( or any cause or cardiovascular ) among individuals aged 65 years and older. However, the results highlight the risk associated with a lower BMI , less than 23 for men and 22.3 for women , which in turn appears associated higher mortality .

" The lack of association between BMI and mortality in the elderly is due to the fact that the BMI in this population , is a poor indicator of body fat, the authors explain. Measuring weight does not differentiate between body fat in lean body mass , or the latter (mainly made up of muscles) gradually disappears with age . "
The waist has been proposed as an alternative measure of obesity, but without success. " Waist circumference alone does not take into account body composition, while the waist / hip circumference ratio is a measure of body shape and , in some way , of abdominal adiposity . S ' it is theoretically possible to have a high ratio while being thin , our data show that people who have a high ratio of waist and higher-than- average hips. We conclude that the observed association between ratio waist / hip circumference and mortality is probably due to abdominal adiposity . "

The authors therefore recommend reviewing the categories of health risk calculated from BMI to assess the impact of overweight and obesity on health, which does not prove to be suitable for more than 75 years. They suggest to rely on the waist / hip circumference ratio in this age group , and recommend to address the problem of under - weight in the elderly .