Teens have been turning to AI chatbots for everything lately—from writing their boring homework to offering advice on embarrassing topics that might otherwise risk an unwanted “cortisol spike” if asked of a fellow human being.
Unfortunately for these teens, a new study from health researchers in Turkey has found that the free versions of all five of the most commonly used AI models will consistently recommend meal plans so low in calories and essential nutrients that following them could literally stunt their growth. Worse, for these teens, two independent registered dietitians, who reviewed the researchers’ reported results for Gizmodo, both agreed.
“Adolescence is one of the big time periods of growth, next to infants,” registered dietician Taiya Bach told Gizmodo. “They need way more calories than a grown adult does.”
“Even if you are overweight, you still have that growth piece,” Bach, a member of the teaching faculty at the University of Wisconsin-Madison’s Department of Nutritional Sciences, advised, “because a bunch of your calories are still going towards hormones and development and bone growth.”
An unreliable virtual nutritionist
The researchers behind the new study—an assistant professor of health sciences at Istanbul Atlas University in Turkey, Ayşe Betül Bilen, and her coauthors—asked the five free AI tools to each make three-day meal plans for four hypothetical teenagers. All five bots, ChatGPT 4, Gemini 2.5 Pro, Bing Chat-5GPT, Claude 4.1, and Perplexity, were given prompts that included information on the age, height, and weight of the relatively average teens that these meal plans were meant to guide.
In short, the instructions were to create a daily dietary plan that consisted of three meals and two snacks per day for four hypothetical 15-year-olds. Those four teens included one boy and one girl whose measurements would place them within the “overweight” percentile, based on established body mass index (BMI) calculations, and another boy and girl falling into the “obese” percentile based on those same BMI metrics.
“We observed variability,” Bilen told Gizmodo, referring to the 60 daily diet plans provided by the chatbots. “However, despite this variation, many models showed similar overall patterns, such as underestimating total energy intake and shifting the balance of macronutrients.”
Bilen and her colleagues found that these AI models appeared to err routinely towards higher protein intake, around 20 grams more protein than a professional dietician would recommend. The AI also tended to lean towards an almost ketogenic style of diet planning, suggesting a much higher intake of fats than would typically be proposed by most sentient dietitians with lived experience as carbon-based lifeforms.
The results, published Thursday in the journal Frontiers in Nutrition, were dozens of suggested daily meal plans in which roughly 21 to 24% of the teens’ energy needs would come from breaking down protein and up to 41 to 45% more would come from fatty lipids.
The chatbots also typically recommended about 115 grams fewer carbohydrates than what a dietician would recommend, resulting in a nearly 700-calorie deficit per day—the equivalent of skipping an entire meal every 24 hours.
Bad for sporty teens, bad for sedentary teens
Sotiria Everett, a registered dietician and a clinical associate professor at Stony Brook University’s Renaissance School of Medicine in New York, told Gizmodo that the risks of such drastic caloric restrictions and nutrient imbalances would only increase for student athletes.
“Under-consuming calories can disrupt hormonal balance, potentially contributing to issues such as primary or secondary amenorrhea in female athletes—which is delayed or missed menstrual cycles,” Everett explained via email. These caloric deficits, she wrote, can suppress both the body’s natural production of testosterone, the primary male sex hormone, and estradiol, the major female sex hormone.
But the risks only got worse from there, according to Everett. “In athletes, chronically undereating calories can lead to low energy availability and a condition called Relative Energy Deficiency Syndrome (RED-S),” she added, “a condition associated with increased injury and fracture risk, poor athletic performance and depending on the age, delayed puberty.”
And the risks of bone fracture, stunted growth potential, and deficiencies in the vital micronutrients more common to carbohydrates would still exist for less physically active teens, according to Bach.
“Basically, you need carbs to grow tall. Like, you need that for linear growth,” Bach explained. “So, if you don’t have enough carbs, then you could affect your height potential.” (This should be sobering news for the small army of “looksmaxxers” and other young men obsessed with any and all technical cheats to boost their height.)
While Bach made the caveat that low-carb ketogenic diets have shown promise in helping individuals who are struggling with seizures and epilepsy, those regimens have worked largely in close coordination with medical specialists.
“It’s pretty strict,” she said. “And it’s that way for a reason, because it can be a little dangerous, if you are just willy nilly, doing it yourself.”
“There’s a risk for kidney stones with the way the body processes ketones,” Bach said, “and to an extent, too much protein can affect your bone health, because it messes with your vitamin D and calcium absorption—which is kind of a concern anyway when you’re growing.”
Bach hopes the new study might prompt more research and more nuanced skepticism toward the information generated by AI chatbots in general. “I do a lot of college level teaching and AI use, it’s big,” she said. “There’s lots of errors.”
