A new study suggests that current body mass index (BMI) recommendations may be unsuitable for older adults.
Caryl Nowson, a professor of nutrition and aging at Deakin University, led a research team that examined the relationship between BMI and risk of death in people 65 and older. The findings indicated the lowest risk was among those with a BMI of about 27.5, which is considered overweight by the World Health Organization. Mortality was said to increase "significantly" among those with a BMI between 22 and 23, the normal weight range.
"It is time to reassess the healthy weight guidelines for older people," Professor Nowson said. "Our results showed that those over the age of 65 with a BMI of between 23 and 33 lived longer, indicating that the ideal body weight for older people is significantly higher than the recommended 18.5-25 'normal' healthy weight range."
The research team reviewed studies published between 1990 and 2013 that reported on BMI and death risk in people 65 years and up. These studies followed 200,000 people over a 12-year period. Results found death risk increased 12 per cent when BMI was between 21 and 22, or the healthy weight range. It increased by 19 per cent when BMI was between 20 and 20.9, which is still considered within normal range. However, those with a BMI of 33 to 33.9, or the obese range, had an 8 per cent increased risk.
"These findings indicate that, by current standards, being overweight is not associated with an increased risk of dying,"
Professor Nowson said. "Rather it is those sitting at the lower end of the normal range that need to be monitored, as older people with BMIs less than 23 are at increased risk of dying."
The professor also noted factors other than BMI need to be considered in terms of ideal body weight.
"Rather than focussing on weight loss, older people should put their efforts into having a balanced diet, eating when hungry and keeping active."
Research was published in the American Journal of Clinical Nutrition.
Cardiovascular and cancer risks are still higher for those who are overweight. This new study also didn't take into account factors such as smoking and illness, which can leave people thinner but not healthy. A study published last month in the journal PLOS ONE that looked at the above factors found that a BMI of 22.5-24.99 was the most favourable for mortality risk.
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