Is whole milk as fattening as people think?

When it comes to milk, it’s been quite controversial. Especially whole milk.

"All you hear all the time is that whole milk is bad for you. No one explains why. They just say it’s bad," Rick Osofsky said, a dairy farmer in Columbia County.

Local dairy farmers say it is actually good for you.

To get the word out, Ann Diefendorf, a local dairy farmer, started painting signs that read, "Drink whole milk. It tastes the best!"

And it’s working.

"People started talking. They started asking questions. How much milk fat is in whole milk?" Diefendorf said.

RELATED: More people are not drinking milk, gravely concerning farmers

The Food and Drug Administration defines whole milk as containing 3.25% milkfat by weight.

Kameron Rowe, a registered dietitian and assistant professor at Russell Sage College, said whole milk can be a healthy part of anyone’s diet.

It has several essential nutrients.

One cup of whole milk has around 150 calories. Compare that to around 90 calories a cup of skim milk.

"What I think it comes down to is looking at overall fat intake and the quality and types of fat that you’re taking in," Rowe said.

Rowe said whole milk is not a bad option. It’s based on your own diet.

"When it comes to consuming whole milk, looking at the totality of fat that you’re taking in your overall diet. As opposed to paying attention to one specific item, like milk."

Now, Diefendorf is spray-painting signs that read, "legalize whole milk choice in schools!" after a federal policy essentially banned whole milk and 2% milk.

"We’re not trying to push that people drink only whole milk. We want them to drink any of the fat content milk. It’s that we want the kids in school to have that choice back," she said.

There has been a push by lawmakers to put whole milk and 2% milk back in schools.

New York Assemblymember, Chris Tague (R – Schoharie) said more milk options in school could in turn help dairy farmers.

"If we’re using more whole milk in our schools, it’s going to help out our dairy farmers because they’re going to need more product from our dairy farmers," he said.

Local dairy farmers say not many people know the fat content of milk, but why?

Watch the video to hear the explanation from a local agricultural historian. She said the backstory dates back to WWII.

13 Investigates went to a school to see if kids are drinking the low-fat milk that is provided to them. That part of the story airs Wednesday, June 8 starting at 5 a.m. and throughout the day.