Got Milk? Not This Generation.

To the marketers trying to reboot milk as a sports drink for Generation Z, Yvonne Zapata seemed like the perfect ambassador. An exuberant 24-year-old marathoner from Brooklyn, she describes herself as a proud Latina runner. Her nickname is Miss Outside.

The Milk Processor Education Program signed her to its 26.2 project, an ambitious effort to provide training, gear, advice and other support to every woman who runs a marathon in the United States this year. In March, Ms. Zapata’s face lit up a giant Times Square billboard. She starred in her own video. Her portrait is one of several anchoring the Gonna Need Milk website.

There is only one problem: Ms. Zapata would rather drink oat milk.

“Dairy milk is good,” she explained in an interview, “but I feel like realistically it’s unhealthy.”

She grew up hearing that dairy products weren’t good for her sports-induced asthma. Then her sister became a vegan and made a strong case against them. But Ms. Zapata is dedicated to getting women with different shapes and from different cultures to embrace running, so she joined #TeamMilk.

“I feel like that’s more important than whether milk is good for you,” she said.

Ms. Zapata is part of the Not Milk generation, teenagers and young adults who grew up ordering milk alternatives at coffee shops and toting water bottles everywhere. Turned off by the no-fat and low-fat milks served at school, worried about climate change and steeped in the increasing skepticism toward the dairy industry on social media, many of them have never embraced milk. Last year, members of Generation Z bought 20 percent less milk than the national average, according to the consumer market research company Circana.

“Nobody drinks regular milk on purpose nowadays,” said Masani Bailey, 30, who created a nostalgic deep dive into the celebrity-driven “Got Milk?” campaign from the 1990s and early 2000s for her TikTok account, @cultureunfiltered.

The dairy industry isn’t banking on nostalgia to save the day. It has embarked on a full-frontal marketing assault intended to do what the “Got Milk?” mustaches on celebrities like Taylor Swift and Dennis Rodman did for previous generations.

“We have to reclaim milk’s mojo,” said Yin Woon Rani, the chief executive of the Milk Processor Education Program, a marketing and education arm of the dairy industry based in Washington, D.C.

The campaign takes several forms. Although the science about the health benefits and drawbacks of milk isn’t settled, some studies have shown that chocolate milk contains basic electrolytes and a precise ratio of carbohydrates to protein that can help muscles recover after workouts. One strategy involves showing athletes like Ms. Zapata that milk is a good sports drink (though the Gonna Need Milk people thought she was more of a milk fan when they signed her up).

Milk processors are betting that supporting women and girls who run, and promoting gender equity in sports — with plenty of post-race chocolate milk — will change some minds. For every woman who joins #Team Milk, the milk processors will make a donation to Girls on the Run, a national nonprofit sports organization.

Milk marketers have also tapped Olympic medalists, women who play football and other sports influencers who swim, climb or play street soccer.

“We sometimes refer to milk as the O.G. sports drink, powering athletes for 10,000 years,” Ms. Rani said.

Some milk marketers have created Shark Tank-like contests that encourage small food entrepreneurs to invent dairy-based products aimed directly at Gen Z. One winner was Spylt, a caffeinated chocolate milk whose tagline is “Chill it. Then chug it!”

All this is not to say that young people don’t eat plenty of cheese, yogurt and ice cream.

“They’re not abandoning dairy,” said John Crawford, a dairy analyst for Circana. “But they certainly are walking away from traditional dairy milk.”

The decline has been happening for decades. Americans’ annual milk consumption peaked at 45 gallons per person in 1945, according to the U.S. Department of Agriculture. It fell to about 23 gallons in 2001, and by 2021 it was down to 16 gallons.

Although Generation Z is the target, millennials laid the groundwork for milk’s identity crisis, with their focus on health and wellness and demand for transparency in the food system.

“I feel like this is another punch line about us: Did millennials kill milk?” said Rebecca Kelley, 39, a content strategy consultant in Seattle.

She and her friends drink almond milk. “I do have some old millennial guilt because I know from a sustainability perspective almond milk is not great,” she said. But she also sneaks in a glass or two of whole milk with spaghetti or a tuna sandwich, despite judgy comments from friends. “For me, it’s a nostalgia play.”

Milk has a tougher battle with Generation Z. Born between 1997 and 2012, it’s the country’s most diverse ever. A bare majority are white, and 29 percent are immigrants or the children of immigrants. Many come from backgrounds in which lactose intolerance is common.

Some have turned to nut milks and other plant-based alternatives, whose sales are expected to grow by more than 9 percent a year through 2027, far faster than milk.

The dairy industry has long waged a battle to keep plant-based alternatives from using the word milk. The Food and Drug Administration in February made it clear that the war is probably over, issuing a draft ruling that drinks made from oats, almonds or other plants can be called milk. The agency did hand dairy producers a small win, recommending that packaging for plant-based drinks make clear the key nutritional differences between their products and cow’s milk.

But dairy milk is still a much bigger player. In the year that ended in November, milk sales were almost $15.7 billion, compared with $2.4 billion for alternative milks.

“People are saying, ‘Oh, plant-based. That’s what’s destroying you,’ ” said Ms. Rani, of the Milk Processor Education Program. “That’s not it. Dairy milk sells as much at retail in a week as oat milk sells in a full year.”

Dairy milk’s real competition is other beverages, like water, both bottled and tap, and specialty coffee drinks.

“People come to work with a Gatorade or a Coke in one hand and a Starbucks cold brew drink in the other,” said Curt Covington, senior director of partner relations at AgAmerica, an agricultural lender. “It has clearly taken away from the milk sector.”

Some young people don’t like milk because they didn’t grow up with it as a dinner-table staple. The Healthy, Hunger-Free Kids Act of 2010 removed whole or 2 percent milk from schools, and required that any flavored milk be nonfat. This led to a genre of social media posts complaining that school milk was disgusting. The Department of Agriculture in 2018 allowed 1 percent chocolate or strawberry milk back into schools.

“We lost almost an entire generation of milk drinkers,” U.S. Representative Glenn Thompson, a Republican from Pennsylvania, told a farming publication.

Dairy farmers say government policies and nutritional standards have demonized whole milk, and that stigma is hurting their livelihoods. In upstate New York, roadsides are dotted with hay bales painted with messages urging the passage of a federal law that would return whole milk to schools.

In February, Representative Elise Stefanik, a Republican from northern New York, reintroduced the Protecting School Milk Choices Act, a direct response to New York’s mayor, Eric Adams, a vegan who has floated the idea of banning chocolate milk in schools and providing more plant-based foods.

But all the legislation and marketing in the world may not help eliminate what many Gen Z-ers refer to as “milk shame.”

Hampton Searcy, 21, has felt it. He lives with three fellow students who don’t like milk in an apartment near Auburn University, in Alabama, so they don’t keep any in the refrigerator. Mr. Searcy grabs a cold pint of whole milk at a convenience store three or four times a week.

“People say, ‘How could you not at least get chocolate milk? Why not get a soda or a sports drink?’” he said. “I just like the taste of white milk. It’s either you like milk or you think it’s weird. And a lot of people I know think it’s weird.”

Haden Gooch, 31, and Katie Gualtieri, 39, want to change that. They tend to about 50 cows on their farm in Leeds, Maine, and sell the milk to Stonyfield Organic.

“If people better understood the nuances of milk as a seasonal product that gets richer in the winter and sweeter in the summer based on what the cows are eating, and saw the effort small dairy farmers put into producing that milk to help feed and keep rural communities alive, they might like milk better,” Ms. Gualtieri said.

In the end, milk’s ace in the hole might not be marathons, YouTube videos or organic farming. The cultural churn that makes something a star one day and destroys it the next could be the saving grace.

Sherry Ning, a writer in Toronto, was only half-joking when she recently tweeted, “The next counterrevolution is the return of whole milk.”

Her theory is akin to what Emily Sundberg suggested two years ago in a New York magazine article arguing that whole milk was making a comeback.

The dairy milk dip coincided with the rise of wellness culture and what Ms. Ning called the influence of tech-bro culture, with its overengineered, health-optimized lifestyle that demonized dairy.

Whole milk, Ms. Ning said, might be the antidote, riding a wave of neo-traditionalism among some members of Gen Z who are embracing a more down-to-earth ethos, centered on nature and regenerative farming. Call it milkcore?

“The return of cow’s milk is kind of the cultural zeitgeist saying, ‘Screw tech. This is too fast and science is going too far,’” she said. “Just go back to normal and stop engineering the way we live.”