A new study from Australia finds that people aged 65 and over with a body mass index in the overweight range live longer and suggests perhaps the World Health Organization guidelines on BMI may not be suitable for older people.
The World Health Organization (WHO) defines overweight as having a body mass index (BMI) greater than or equal to 25, and a BMI of 30 or over as obese. BMI is equal to a person's weight in kilos divided by the square of their height in meters (kg/m2).
Caryl Nowson, professor of nutrition and aging at Deakin University in Melbourne, and colleagues looked at links BMI and risk of death in people aged 65 and over, and found those with the lowest risk of death had a BMI of around 27.5.
They also found those with a BMI between 22 and 23 - considered to be the normal weight range - had a significantly higher risk of death.
They say their findings, which they report in the American Journal of Clinical Nutrition, question whether the WHO guidelines are suitable for older adults. Prof. Nowson suggests it is time to reassess them, and adds:
"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."
For their study, the team pooled and re-analyzed results from studies published between 1990 and 2013 that had examined links between BMI and risk of death in people aged 65 and over.
Altogether, the analysis covered over 200,000 older people followed for an average of 12 years, and revealed, with reference to BMI in the range 23.0 to 23.9, that there was no increased risk of death for people in the overweight range, but:
- Risk of death increased by 12% when BMI was between 21 and 22 (near the middle of the healthy weight range)
- Risk of death increased by 19% when BMI was between 20 and 20.9 (still within the healthy weight range)
- Risk of death increased by 8% when BMI was between 33 and 33.9 (in the obese range).
Prof. Nowson says for people aged 65 and over, by the WHO standards, being overweight is not associated with an increased risk of death, and that "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."
Advice on body weight for older people needs to look at more than just BMI
The study suggests that people aged 65 and over with a BMI in the overweight range live longer and may not need to lose weight.
She suggests advice on ideal body weight for older people should take into account factors other than BMI, and:
"Factors such as chronic diseases and the ability to move around need to be considered as there is no real issue with being in the overweight range unless it is preventing people from moving around freely."
She says older people need to get off the weight loss bandwagon and focus instead on getting a balanced diet, eating when hungry and keeping active.
She says there is a real risk of malnutrition among older people from putting too much emphasis on dietary restrictions.
"Malnutrition in older people is not well recognised as this can occur even when BMI is in the overweight range," she adds.
Meanwhile, Medical News Today recently reported a study that found extreme loneliness is a risk factor for premature death in seniors. The University of Chicago research found loneliness was tied to a 14% higher risk of death making it nearly as potent as disadvantaged socioeconomic status, which carries a 19% increased risk of early death.
Written by Catharine Paddock PhD