Maintaining a reasonable body weight is an on-going problem for many people. If they are not on a diet, they seem to gain weight without limit. They become rounded, fat, obese and downright unsightly. All evidence suggests that this increased weight is not healthy. Along with just weight control, there are many fads in diet.
Some animals eat and drink when hungry.
They generally stop when full. They tend to eat what they want and can easily leave the rest. I have an idea. Maybe man is driven to our overeating for other reasons than hunger. We are brought up to clean up our plates before we can have dessert or leave the table.