Protein Diet Coke is all the rage. Is it actually healthy for you?

But one of the latest overlaps with social media’s growing obsession with protein: mixing Diet Coke with a Fairlife protein shake.

Many people on TikTok claim that the trend started in Utah in September, after one woman posted a video of herself filling a huge cup with Diet Coke and pouring in a vanilla Fairlife protein shake. Her video now has over 2.6 million views.

“Welcome to Utah where protein Diet Coke is currently trending,” the text on her video read.

@beccers_gordonn Protein diet coke gets a 10/10 for me. Gotta love utah gas stations #utah #gasstation #soda #proteindietcoke #dietcoke #utahcheck #swig ♬ Did Somebody Say HipOpera – Latto & Christina Aguilera

“I love it,” another TikTokker said after she, too, tried it. “I think I’m going to start doing this every day.”

It’s hard to say if the drink is worth the hype—or if it could be considered a healthy beverage. Here’s what one expert thinks about whether the protein Diet Coke is healthy or not.

How much protein you need each day

Protein is a vital structural component of our cells, tissues, hormones, and enzymes, and numerous other bodily functions. A continual supply of amino acids through the protein we eat is crucial for cell and tissue growth and repair.

While wellness culture often celebrates high-protein diets—like keto or carnivore, dietitians have pointed out that most adults are meeting or exceeding daily protein requirements.

“If you’re meeting your caloric needs … you’re meeting your protein needs,” registered dietitian Abbey Sharp previously told Fortune. 

“Whether a person goes to the gym or not, we as human beings who are not elite athletes generally do not need extra protein,” says Stella Volpe, president of the American College of Sports Medicine and a registered dietitian. “Putting [protein] in something like a soda is not the best way for us to get our protein, anyway.”

Volpe recommends choosing whole-food sources of protein whenever you can—especially to ensure you’re absorbing the protein adequately. For people under age 45, she says, the ideal quantity for protein absorption in one sitting is 20 grams of protein. For those over age 50, that number is around 30 to 35 grams of protein in one sitting.

Going on Volpe’s general protein recommendations, the 26-gram version will likely be more easily absorbed by the body, as most of these shakes have a protein content that’s “really high and likely not really needed by the average person.”

The U.S. Department of Agriculture’s Dietary Guidelines for Americans recommends 10% to 35% of your daily calories come from protein sources. If you’re following a 2,000-calorie per day diet, that would be 200 to 700 calories from protein sources.

Drinking the protein Diet Coke in the hopes of meeting your protein goals likely isn’t necessary, especially as the U.S. Department of Agriculture reports that nearly 60% of the U.S. population—ages 1 and older—eat more than the dietary protein recommendations, found in the Dietary Guidelines for Americans.

Aspartame, caffeine, and other additives

Concerns about Diet Coke usually stem from worries about aspartame, an artificial sweetener that was labeled by the World Health Organization as a “possible carcinogen” in July 2023.

Sharp believes people shouldn’t be concerned, however, as she said in a TikTok she posted about the protein Diet Coke. She lets her viewers know that aspartame is not poisonous in the normal quantities it’s consumed, so there’s no need to be worried.

The FDA’s acceptable daily intake of aspartame is 50 mg per kilogram of body weight. A 12-ounce can of Diet Coke has about 180 mg of aspartame, meaning a person weighing 68 kg (about 150 pounds) would have to drink 19 cans to reach that limit. 

However, it’s important to keep track of what you’re eating, as you might be consuming other sources of aspartame in things such as other diet sodas, sugar-free gum, cereals, and sugar-free or diet juices. 

It’s not just aspartame, though. Other ingredients, like caffeine and phosphoric acid, are other sources of worry when it comes to Diet Coke.  

One can of Diet Coke has 46 milligrams of caffeine in it; however, many of the people concoting their protein-Diet Cokes are almost filling up a 32-ounce plastic cup before adding in the protein shake. That would be nearly 150 milligrams of caffeine—well below the FDA’s daily limit of 400 mg, but still concerning to Volpe , because people may be drinking that in addition to a cup or two of coffee.

“Caffeine for some people can be very negative—whether they have heart disease or hypertension, and it can really affect their sleep,” says Volpe.

Another concern about Diet Coke is the phosphoric acid it contains, Volpe says.

“In any type of soda that has phosphoric acid, that can actually offset calcium absorption,” Volpe says. 

If people are looking to get in more protein, Volpe asks: “Why not just have Fairlife?”

Be aware, though, that Fairlife contains additives of its own—including maltodextrin and sucralose, both of which can affect the body’s balance of gut bacteria.

Is it worth the hype?

Sharp tried the protein Diet Coke for herself to see what all the fuss was about. And once she did, she understood why so many people were drinking it.

“This tastes like an ice cream float,” Sharp said in a TikTok. 

While the protein Diet Coke might be a nice treat every once in a while, Volpe wouldn’t encourage anyone to drink it, since most people likely don’t need the additional protein, and because of the ultra-processed ingredients found in Diet Coke and the protein shake.

Volpe is more concerned about the ultra-processed nature of Diet Coke than Fairlife, however she still encourages people to turn to more whole food ingredients to get in their protein.

“Making choices about our food intake are ours to make, but we do better with less processed choices,” Volpe says.

For more on protein:

• You might be overdoing it on protein and not getting enough of another vital nutrient, dietitians say
• Here’s exactly how much protein you need based on your workout routine
• What’s the scoop on protein powder? Nutrition experts share 3 things to know about the popular supplement