Halo Top, a six-year-old company that makes low-calorie, high-protein ice cream, is now the best-selling pint in U.S. grocery stores, surpassing heavyweights like Ben & Jerry’s and Häagen-Daazs. (In 2016, Halo Top sales reached $66 million, up 2,500% from the previous year.) While other brands market themselves as a rich, indulgent treat, Halo Top advertises itself as a “healthy” food.

“We live in an era of an obesity epidemic. It’s not a joke; it’s a serious problem that we need to address,” CEO Justin Woolverton told Fortune. “We strongly believe Halo Top is a healthy alternative to ice cream, and here’s why. We contain far fewer calories, less sugar, and more protein than full-fat ice cream.”

But nutritionists aren’t buying it.

“Marketing ice cream as healthy is an oxymoron if I’ve ever heard one,” Marion Nestle, a professor of nutrition, food studies, and public health at New York University, tells Fortune in an email. “This fits perfectly in the category of ‘just because it’s a slightly better choice does not mean that it is a good choice.’”

Halo Top’s advertising leans heavily on the idea that consumers can eat an entire pint without feeling guilty (its lids are emblazoned with the command to “stop when you get to the bottom.”) While less caloric than regular ice cream, a pint of Halo Top still contains more than 10% of the daily recommended limit, says Sharon Akabas, the associate director of the Institute of Human Nutrition at Columbia University.

“With two-thirds of the US adult population overweight or obese, we don’t have much wiggle room for ‘discretionary calories,’” she says. Most nutritionists and health organizations define a healthy diet as eating “fewer processed foods, and selecting a dietary pattern rich in plant-based foods,” she adds. “Halo Top is neither.”

Barry Popkin, a professor of nutrition at the University of North Carolina, has questions regarding erythritol, the sugar alcohol additive Halo Top uses in its recipe in order to cut back on sugar. Not harmful in small portions, some studies have found erythritol can cause diarrhea and other bloating symptoms when consumed in large quantities (Halo Top says you would need to eat around 3 pints for this to be a concern.)

Popkin also worries the company’s messaging will reinforces bad eating habits, as it runs in direct opposition to one of the basic tenets of maintaining a balanced diet: moderation.

“I’d rather have the richest and most delicious ice cream in the world, but by the scoop, not pint,” says Nestle.

Halo Top pushed back on the notion that their products could lead to overconsumption: “I think most people eat Halo Top knowing it’s a lower-calorie version of full-fat ice cream. Just because they eat a pint of Halo Top doesn’t mean they’ll think it’s okay to eat a pint of, say, peanut butter. Honestly the argument kind of confuses me.”

Finally, the nutritionists point out that Halo Top is able to call itself a health food because the term “healthy” doesn’t actually mean much of anything. It’s not “standardized or regulated by any official or even knowledgeable organization,” says Akabas. “Because of that, anything can be marketed as healthy.”