"Despite having been demonized in the past, real grass-fed butter is one of the healthiest fats on the planet."
Grass-fed butter (and it makes an enormous difference what the cows from which the milk came actually ate) provides CLA (conjugated linoleic acid) and Vitamin K2 (long implicated in helping the absorption of calcium and Vitamin D).
Does that mean you can chomp on a stick of butter all day long, eat nothing else, exercise and lose weight while you build muscle? Of course not. But cultures which have long incorporated these kinds of healthy fats into their diet are the same cultures which show markedly lower levels of heart disease and heart attack risk.