I breast fed my daughter until she weaned herself at four years old.
Started her on solid food at about 4 months if I recall correctly.
She's 10 now and lean--all muscle--and one reason is because she doesn't eat a lot of food at once. When her body has had enough, she stops eating, and that's it--she will not budge.
So I got to thinking: when a baby breastfeeds, they eat until they're full and then they pop off and do something else. The feedback loop is completely natural & unforced--there's nothing other than their own feeling of satiety to influence how much they eat.
I have to think this taught her to know when she's had enough.