Ever since 1985, the government has had the same recommendation: three cups of skim milk a day. During the rise of the fat fiend, the USDA declared fat in foods the enemy to a healthy, and skinnier, lifestyle. In order to reduce Americas fat intake, they declared whole milk an enemy, and pushed for skim, along with its lower fat content friends.

According to some, this has been a real victory. "When I was in Congress, you couldn't even get low-fat milk in school lunches!" declared Dan Glickman, the former U.S. Secretary of Agriculture and congressman from Kansas, at a recent Atlantic panel discussion on health care. Indeed, skim milk has become one symbol of the fight for healthy eating and, by extension, a healthier population.

When Michelle Obama rolled out her "Let's Move!" campaign in 2010, skim milk also played a role, especially in the movement’s school lunch reform efforts. Some groups, like the International Dairy Foods Association, also took the opportunity to create their own campaigns advocating more milk-drinking among kids.

But recently, a few researchers and writers have begun to doubt the nutritional value of the big push to drink skim. This fall, a pair of researchers from Boston Children's Hospital and the Harvard School of Public Health published an editorial note in JAMA Pediatrics questioning the science behind the recommendations. They argued that drinking low-fat milk leaves people feeling hungry, leading them to eat more -- usually carbs.

Companies also create sugar-filled, flavored alternatives to make milk more appealing to kids, which offsets the potential benefits of low-fat content.

A different study published in the Archives of Disease in Childhood this spring suggested that skim and low-fat milk don't prevent childhood weight gain -- in fact, they make kids heavier. Kids who drank whole or two-percent milk between ages two and four had a slightly lower body mass index than kids who drank one percent or skim milk. Another study had a similar finding in 2010.

But the fact is that scientists don't agree, while public health officials still seem adamant about the importance of skim, and this points to larger complications in obesity prevention. As the panelists at the Atlantic discussion pointed out, powerful groups in the agriculture industry, including sugar and dairy farmers, have a deep interest in public campaigns to overhaul school lunches and change Americans' eating habits.

And while certain norms -- like the importance of drinking low-fat milk to eliminate dietary fat -- have become an accepted part of public health campaigns, they aren't necessarily as effective as leaders make them seem. Glickman might envy the success of public health campaigns led by Michelle Obama and other government leaders, but his assumptions -- including the infallibility of skim milk --reveal the difficulties of orchestrating major public health changes from the top.