A study from the University of Western Australia shows a lower rate of dementia among slightly overweight elderly men.
The study showed that a slight increase of fat later life may not be detrimental but may in fact have a positive effect and may be considered an indication of good health.
The findings titled 'Body Adiposity in Later Life and the Incidence of Dementia: The Health in Men Study' shows that elderly men who are considered overweight have a lower chance of developing dementia than those within the normal weight range.
The study headed by UWA Chair of Geriatric Psychiatry Osvaldo Almeida followed more than 12,000 men aged 65–84 years during 1996–2009.
It aimed to determine if being overweight later in life increases the incidence of dementia.
Prof Almeida says the results were unexpected as there is good evidence that overweight or obese younger adults have an increased risk of cognitive decline as they get older.
“When we designed this study this is not something that we were expecting to find,” he says.
“We were expecting to find the opposite, that obesity would increase the risk of dementia.
”Prof Almeida says one possible explanation is survivorship bias, where people who are overweight later in life are unusually healthy compared with normal weight people in the same age group.
Another explanation is physiological changes as people age, causing the body to protect itself from degenerative effects.
“The fat tissue behaves a little like an endocrine organ and releases a number of substances into the bloodstream that have different actions on the body.” Almeida said.
“In animal studies we know that leptin, which is one of the substances that fat tissues produce, seems to have a neuro-protective effect on the hippocampus which is an area of the brain where cells are important for memory.
”The study showed that a slight increase of fat later life may not be detrimental but may in fact have a positive effect and may be considered an indication of good health.
By current standards a person with a Body Mass Index (BMI) below 25 is considered to be in the normal weight range with 25–30 considered overweight and above 30 obese.
Studies have shown that people who are slightly overweight in later life have lower mortality rates than those with normal weight.
“I wish to emphasise the slightly overweight. Rather than have a BMI of below 25 we are talking about BMI's around 27 as being good.
“You wouldn't expect to get a 70 year old to run at the same speed as a 20 year old but you expect them to have the same body composition.”
Prof Almeida says this approach of one size fits all is probably incorrect.
Current health guidelines for older people are the same as that of a young to middle aged adult and this is something Prof Almeida says she would like to see addressed.
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