That makes a lot of sense. Too lazy (and ignorant about endocrinology and neurology) to research your claims, but I have heard about elderly just stacking their meals on wheels in the fridge without ever touching them, and then either ending up in a home, or dropping dead from starvation. If the satin story is true, that might be an excellent explanation for the difference. Edit: for clarity, the deleted comment said:     Being a bit overweight is actually protective for the elderly. One possibility is that as you age, your ability to taste food and your desire to eat decreases. That's why you actually want to assess the elderly for malnutrition. Perhaps being overweight is linked to not having malnutrition and that's why being overweight is correlated with reduced dementia risk. Additionally, overweight elderly are more likely to be on cholesterol medications. Specifically, they're often put on a "statin." Studies indicate that statins may decrease the risk of dementia. As such, perhaps being overweight decreases the risk of dementia because they're on protective meds.