Elderly ‘live longer if they are overweight’
Reported February 14, 2010
Being overweight can help elderly people live longer, according to the most detailed study ever conducted into the health and ageing of those aged between 70 and 75. Being underweight, on the other hand, can lead to an increased risk of mortality.
The study also found a sedentary lifestyle is more risky for women of all ages than it is for men.
“This study has demonstrated that, for people who have survived to the age of 70, the risk of death is lowest among those with a BMI [body mass index] classified as overweight,” said Professor Leon Flicker, one of the world’s most eminent specialists in geriatric health. “Those in their seventies who were classified as normal weight had a higher risk of death than the overweight group.”
The link between weight and mortality remained true for all of the most common causes of death, including cardiovascular disease and cancer.
“Even after removing the effects of early mortality, those who were overweight were still at lowest risk,” added Flicker, whose research will be published in the Journal of the American Geriatrics Society. “This is a finding consistent with the observation that weight loss in older age groups is associated with greater incidence of death.”
The World Health Organisation defines weight categories using the body mass index – a person’s weight in kilograms divided by the square of their height in metres. The optimal weight is a BMI of 18.5 to 24.99; overweight is defined as a BMI of 25 to 29.99, while a BMI of 30 or higher would be considered obese, and less than 18.5 underweight.
More than 60% of adults in the UK are overweight or obese, compared with 53% since 1993, according to the Health Survey for England 2007. About 44% of adults aged 65 or more are classified as overweight in the UK, with men more likely to have a higher BMI than women. Just under 30% of all those aged 55 to 74 are obese.
Flicker, a professor of geriatric medicine and executive director of the Western Australian Centre for Health and Ageing, admitted he wasn’t sure why excess weight protected older adults. “We can only hypothesise,” he said. “But it may be that, as we age, the presence of nutritional and metabolic reserves – ie, fat – are advantageous.”
Flicker said the extra weight could give older people reserves to recover from stresses such as surgery or pneumonia. “If you develop an illness, a little more reserve gives you a greater chance to recover from that illness,” he said.
The research, which was based on data from two long-term studies of 9,240 adults aged 70 to 75, showed that adults who were overweight were on average 13% less likely to die from any cause over a 10-year period, compared with those of normal weight. Those who were underweight were 76% more likely to die, while obese elderly people had the same mortality risk as those of normal weight.
“Women who do not take exercise are twice as likely to die as women who get regular exercise, regardless of their BMI,” he said. “The same effect is seen in men, but to a lesser degree: a sedentary lifestyle was associated with a 28% increase in death among men.”
The findings are the latest to cast doubt over whether BMI should be used to establish the ideal weight across all age groups. Some experts say that BMI is an unreliable marker for body fat or health in the elderly, who can often experience a fall in BMI as they age thanks to a loss of muscle mass and bone density.
But Flicker’s research identified that the “minimum mortality risk” for older people was a BMI of 26.6 in men and 26.26 in women. For men and women with BMIs that were classified as normal, the risk of death increased as BMI decreased so sharply that the estimated risk of death for men and women at the lower end of the normal range was almost double the risk in those who were overweight.
But preventive health experts questioned Flicker’s conclusions. “There is a difference between survival and quality of life,” Dr Joanne Manson, a Harvard Medical School professor.
Manson said being overweight was a major risk factor for many health problems, including Type 2 diabetes, hypertension, stroke, coronary disease, cancer and loss of physical function. “These are strong enough reasons to strive for a healthy weight and avoidance of obesity,” she said. “Moreover, given all the adverse effects of obesity on health, it isn’t biologically plausible that being overweight would lower mortality risks.”
Source : Guardian News and Media Limited
