The guidelines immediately stirred controversy, with critics on the left concerned about unequal access to treatment and conservative commentators suggesting that the guidelines offer an easy out for poor lifestyle choices. Critics from across the spectrum have noted the potential long-term consequences of putting children on drugs and performing irreversible surgery on teenagers.

"Lifestyle choices" typically mean more exercise—along with less processed food and more fruits and vegetables in the diet—but no one in the mainstream is suggesting that the solution is to allow children to eat more natural saturated fat.

Years ago, my co-author and colleague Mary Enig, who held a doctorate in nutritional sciences, had an interesting conversation with an official at the U.S. Department of Agriculture. The agency had researched the best way to fatten pigs—research that was never published. When they fed pigs whole milk or coconut oil, the pigs stayed lean—they found that the best way to fatten pigs was to feed them skim milk.

The Department's dietary guidelines stipulate reduced fat milk for all Americans above the age of 2. Could this policy—initiated in the 1990s—explain the increase in obesity among American children? A couple of studies indicate that this could be the case.