According to a new study published in Nutrition, a scientific journal, plant-based pizza and other meals might not be as good for you as you think—at least, if you’re ordering them from fast-food joints.

As reported in The Times, the study’s lead author, Mikołaj Kamiński of the Poznań University of Medical Sciences in Poland, said the team’s findings “revealed that plant-based fast-food meals were more likely to contain more carbohydrates and sugar than meat-based equivalents.”

For the study, the researchers analyzed the nutritional content of 1,868 meals, including pizza, sandwiches, pastas and salads, from 50 fast-food chains across five countries—the United States, the United Kingdom, Canada, Poland and Australia. They looked at calorie content, allergens, and the amount of nutrients, fiber and salt in each meal.

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They found that plant-based meals provided less protein and sodium and higher levels of carbs and sugar compared to meat-based meals.

Of course, cutting back on sodium isn’t a problem, and there are other sources for the protein the body needs. But there was more disturbing news for vegetarians and vegans who think they’re making a healthier dietary choice. “Surprisingly, our study shows that plant-based meals are not associated with lower calories, which consumers may not realize,” Kamiński said in The Times story. “This really emphasizes the importance of making informed food choices, especially when it comes to consuming fast food—even more so if you suffer from a metabolic disorder like type 2 diabetes. It exposes the illusion that plant-based alternatives of popular fast-food dishes are automatically a healthier choice.”

Going with vegan meats in your sandwiches won’t necessarily help with allergens, either. The study found that meals with traditional meats are more likely to contain allergens like dairy, eggs and shellfish, while plant-based meats are more likely to include allergens like sesame, seeds and nuts.

To be clear, the study focused on plant-based meals from fast-food restaurants only. And there’s little doubt that a diet high in real vegetables, including veggie-topped pizzas, has many health benefits.

In fact, a November 2023 study by Stanford University concluded that a vegan diet improves overall cardiovascular health and is better for you than eating meats.

In that study, Stanford researchers worked with 22 pairs of identical twins. “Although it’s well-known that eating less meat improves cardiovascular health, diet studies are often hampered by factors such as genetic differences, upbringing and lifestyle choices,” a Stanford University press release states. “By studying identical twins, however, the researchers were able to control for genetics and limit the other factors, as the twins grew up in the same households and reported similar lifestyles.”

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The Stanford study matched one twin from each pair with either a vegan diet or an omnivore diet over eight weeks. Both diets included plenty of veggies, legumes, fruits and whole grains while eliminating sugar and refined starches. The vegan diet excluded meat as well as animal products like eggs and milk. The omnivore diet included eggs, dairy, chicken, fish, cheese and other animal products.

“The authors found the most improvement over the first four weeks of the diet change,” Stanford University reported. “The participants with a vegan diet had significantly lower low-density lipoprotein cholesterol (LDL-C) levels, insulin and body weight—all of which are associated with improved cardiovascular health—than the omnivore participants…The vegan participants also showed about a 20% drop in fasting insulin—higher insulin level is a risk factor for developing diabetes. The vegans also lost an average of 4.2 more pounds than the omnivore.”

“Based on these results and thinking about longevity, most of us would benefit from going to a more plant-based diet,” said Christopher Gardner, the study’s senior author and a Stanford University professor of medicine. He added that a vegan diet “can confer additional benefits such as increased gut bacteria and the reduction of telomere loss, which slows aging in the body.”

But Gardner added that you don’t have to go fully vegan to improve your health. “What’s more important than going strictly vegan is including more plant-based foods into your diet,” he said.

An interesting sidenote: Another study published in Nutrition last November examined emotional responses to plant-based meat alternatives, in particular plant-based burgers. “In an online survey, 279 Dutch adults (meat eaters and flexitarians) were shown pictures of a plant-based burger and a meat burger in random order,” the study’s abstract explains. “They were asked to imagine eating the burgers, and then to rate the expected experience of 13 food-evoked emotions and liking for each burger on a 7-point Likert scale. Participants also had to indicate which of the two burgers they would choose to eat.”

The results? Participants expected to feel more “proud” and “cool” and less “guilty” and “worried” when eating a plant-based burger. But they expected to feel more “happy” and less “bored” when chowing down on a meat-based burger.