Excess belly fat makes you more susceptible to memory loss and even dementia—and now scientists think they know why. The link between abdominal fat and brain shrinkage was discovered back in 2010, but a new study has pointed to a possible cause: As Scientific American puts it, "Your liver could be 'eating' your brain." The liver burns belly fat using a protein called PPARalpha, the researchers found, which just happens to be the same protein the hippocampus uses to process memory.
If you have a lot of excess fat, the liver needs to work overtime, and once its local PPARalpha supply is exhausted, it'll steal more from other parts of the body, including the brain. Their results confirm earlier estimates that obese people are thus 3.6 times more likely to develop dementia than their skinny friends.