For many overweight adolescents, asking a chatbot for a slimming menu seems simpler than entering the door of a doctor’s office. In just a few seconds, ChatGPT, Gemini or Claude offer detailed, beautifully presented menus that promise to “eat better” and lose weight. The story seems ideal.
However, a team from Atlas University in Istanbul tested five free AI models on four fictitious profiles of 15-year-olds, overweight or obese, by asking them for three-day menus with three meals and two snacks. Result: compared to the plan established by a dietitian, the meal plans provided on average nearly 700 calories less per day, the equivalent of one full meal less. And the nutrients were also out of balance.
A study quantifies the “missing meal” of AI menus for teenagers
The researchers analyzed 60 plans generated by ChatGPT-4, Gemini 2.5 Pro, Bing Chat-5GPT, Claude 4.1 and Perplexity. In addition to the energy deficit of approximately 695 kcal, the AI offered on average 21-24% of calories as protein, 41-45% as fat, and only 32-36% as carbohydrates, far from the recommended ranges for adolescents.
“We show that dietary plans generated by AI models tend to significantly underestimate total energy and key nutrient intake compared to guideline-based plans prepared by a dietitian.“, explained Ayşe Betül Bilen, lecturer at Istanbul Atlas University, in an article published by
Frontiers in Nutrition.
For comparison, the U.S. National Academies of Sciences recommend that 15 to 20 percent of calories come from protein, 30 to 35 percent from fat, and 45 to 50 percent from carbohydrates at this age. “AI-generated eating plans consistently deviated from recommended macronutrient balance, particularly problematic for adolescents“added Professor Bilen.
The AI systems suggested a higher protein intake, around 20g more than advised by the dietician, making protein account for around 21-24% of the total energy consumed. Similarly, the AI’s recommended fat intake exceeded that of the dietitian’s dietary plans, with fat constituting 41–45% of total energy.
In contrast, the amount of carbohydrates was significantly reduced in the AI diets, with an average difference of around 115g, implying that only 32-36% of energy came from carbohydrates.
Why “skipping” 700 calories a day is risky as a teenager
According to the Turkish team, this daily “missing meal” occurs precisely during a phase when the body is consolidating bones, muscles and the brain. Adolescence is one of the great times of growth, like infants. They need many more calories than an adult.
In athletic adolescents, these repeated deficits do not only affect the weight curve. This lack of energy can disrupt hormones and promote amenorrhea, with delayed or absent menstrual cycles. Researchers also suggest a relative energy deficit syndrome, associated with more injuries, fractures and sometimes delayed puberty.
Researchers call for using AI as a simple support, not a dietician
For Ayşe Betül Bilen, these errors are due to the fact that AI models mainly generate plausible and attractive responses, fueled by popular diets rich in protein, rather than by official guides for adolescents.
“AI models are primarily trained to generate answers that appear plausible and easy to use, rather than answers that are clinically accurate“, explains Professor Bilen. “Our results suggest that they may rely on generalized or popular dietary patterns instead of fully incorporating age-specific nutritional needs.“.
Since not all teens have the option to consult a dietitian to plan their meals, the team advises caution when using AI tools to create meal plans. It is also recommended that adolescents be wary of diets that are too strict or those that favor excessive consumption of proteins or fats.