Ever-growing waistlines could fuel a big increase in the number of people with dementia in the future, researchers have warned.
Previous studies have shown that being overweight in middle age increases the odds of developing the mental disorder.
Data presented at the European Congress on Obesity suggests stemming the rise in obesity will cut dementia.
The Alzheimer's Society charity said regular exercise and a healthy weight were important for reducing risk.
Piling on too many pounds is known to be bad for the body, but there is growing evidence that it is also bad for the mind.