NEW YORK — The size of a man’s biceps and his waist could provide a more accurate picture of his mortality risk than body mass index alone, according to British researchers.
A study of 4,107 men aged 60 to 79 found those with a waist of less than 102 centimeters and above-average muscle mass in their upper arms were the least likely to die over a six-year period, according to Dr. S. Goya Wannamethee of Royal Free and University College Medical School in London.
Body mass index, on the other hand, was only linked to mortality among very thin men, who were at increased risk of dying.
“In older men especially, we should not just be measuring weight but also their waist circumference and their muscle mass as measured by mid-arm muscle circumference,” Wannamethee told Reuters Health.
As people age they typically lose muscle mass and gain belly fat, Wannamethee and colleagues note in a report in the American Journal of Clinical Nutrition.
These changes mean BMI may not provide an accurate picture of obesity and overweight in older people.
The researchers set out to determine whether belly fat and muscle mass might be more precise predictors of mortality by making several measurements of body composition in 4,107 men, 713 of whom died during the study’s six-year follow-up period.
A man’s risk of dying during the study dropped as his muscle mass rose, while both BMI and waist circumference alone showed little relationship to mortality.
Combining muscle mass and waist size provided the most accurate gauge of death risk.
Men with waist circumferences greater than 102 cm and above-average muscle mass were 36 per cent more likely to die than those with smaller waists and bigger-than-average muscles, while those with big bellies and small muscles were at 55 per cent greater mortality risk.