Many of the reasons that we eat is because we enjoy eating. Many older folks eat because they enjoy eating also, but many of them eat because the know they have to eat because they ll feel bad if they don t eat. That they must eat. They ve lost some of the pleasurable or hedonic qualities of eating. Swallowing disorders are common also, especially in dementia and stroke.
People can have a lot of trouble getting adequate calories and protein in orally.
The most important dental problem is mal-fitting dentures, which is so common. It causes this it fuels this cycle. You lose weight, your Social causes, such as poverty and alcoholism. Bereavement, particularly for widowers is a big cause of malnutrition in the elderly. Particularly men who have spent their whole life being waited on by their wife.