Our bodies use the fat to process the calcium properly. At least that is what I remember from nutrition class. We were told that calcium from low or no fat dairy could not be absorbed properly into the teeth and bones. That was some time in the 1980s.
My teacher was British for what that is worth.
I never saw the point of drinking skim milk. People eat highly processed sugary breakfast cereal,
and pour skim milk on it to make it "healthy".
Growing up my mother was big on feeding us whole milk and real butter. Want dessert? Grab an apple, kid.
