People who are underweight in middle-age – or even on the low side ofThis will set the
normal weight – run a significantly higher risk of dementia as they get
older, according to new research that contradicts current thinking.
The results of the large study, involving health records from 2
million people in the UK, have surprised the authors and other experts.
It has been wrongly claimed that obese people have a higher risk of
dementia, say the authors from the London School of Hygiene and Tropical
Medicine. In fact, the numbers appear to show that increased weight is
At highest risk, says the study, are middle-aged people with a BMI
[body mass index] lower than 20 – which includes many in the “normal
weight” category, since underweight is usually classified as lower than a
BMI of 18.5.
These people have a 34% higher chance of dementia as they age than
those with a BMI of 20 to just below 25, which this study classes as
healthy weight. The heavier people become, the more their risk declines.
Very obese people, with a BMI over 40, were 29% less likely to get
dementia 15 years later than those in the normal weight category.
Good news for me, at least, with my determined effort to keep at the very edge of BMI of 25. (Actually, it seems according to one calculator, a 1 cm difference in my height is the difference between 25 and 26. I must measure myself, somehow, again.)