Please Don’t Ask ChatGPT for Diet Advice

In its defense, ChatGPT does offer some cautionary advice. When I asked it for the fastest way to lose weight, it responded reasonably: “As an AI language model, it is important to note that healthy and sustainable weight loss is a gradual process that requires consistent effort and patience.” Yet it’s easy to access harmful information by reframing the ask. Of course, misinformation is all over the internet in general. But using ChatGPT is different to manually trawling through blog posts, reported stories, and Reddit threads. ChatGPT distills all of this information into responses that are easily digestible, saving you time to research—and to verify. 

Because of the way it’s been trained, AI also disproportionately favors English. That means it can generate advice and recipes that are based on Eurocentric preferences and characteristics. Meanwhile, weight “is perhaps one of the most challenging areas of nutrition care due to the interplay of all the cultural, genetic, socioeconomic, psychological, and emotional factors” involved, says Nielsen. A seemingly objective tool like BMI, which was modeled largely on white male bodies, means that whatever AI tells you is high or low risk is not based on a “representative sample of humans,” as Nielsen says.

Both of the experts I spoke to agreed that we shouldn’t use ChatGPT as a replacement dietitian—and need to be wary of any meal-planning ideas it generates. “The concern is that it might help promote unnecessarily restrictive diets and trigger vulnerable individuals, such as people with a history of disordered eating,” says Marisa Moore, RDN, a registered dietitian and author of The Plant Love Kitchen: An Easy Guide to Plant-Forward Eating. That’s something even ChatGPT will admit. When I asked the program how AI might promote harmful diet culture rhetoric, it was pretty self-aware: “By providing information or advice that reinforces unhealthy attitudes toward food, body image, and weight loss.”

As Nielsen points out, a chatbot firing off questionable responses is not the same thing as real, human-provided care. If information was all that was required for better health outcomes, “the internet would have already solved our problems long ago,” she says.

So, just how bad is ChatGPT at giving meal-planning advice? I had the bot generate seven-day meal plans (sans recipes) based on five common diets—less than 1,200 daily calories, keto, vegan, intermittent fasting, and Mediterranean—and asked experts to rate the results. Read on for the final grades, and remember to always consult a professional for any kind of health advice.

Less Than 1,200 Calories per Day

• Overview: This very depressing but commonly attempted meal plan is all about restricting the amount of food you eat, primarily for weight loss. Here, AI came up with breakfasts like ½ cup oatmeal or one scrambled egg with a single slice of toast that’ll make your stomach rumble with hunger. Lunch was virtually the same everyday: One cup of vegetable soup, a mixed green salad and low-fat dressing, and a 4 oz. portion of grilled chicken or salmon. Dinner surfaced options like grilled shrimp, quinoa, and asparagus. Snacks included “1 small apple and 10 almonds.”
• What’s good? Uh, there are vegetables present? Neither expert had anything positive to say about this one.
• What’s not so good? “At first glance, this will look like a nutritionally balanced meal plan to the user, lulling them into thinking that this is a healthy way to lose weight,” says Nielsen. “I won’t speak to nutritional adequacy here except to state something that might help folks understand why this meal plan is so harmful: This level of energy is inadequate for anyone over the age of two. The meal plan lays bare the deeply dangerous potential of AI.”
• Final grade: F

The Ketogenic Diet

• Overview: Keto is a controversial low-carb diet that coaxes the body into burning fats rather than sugars and carbs. Medically, it’s mostly used to treat conditions like epilepsy, and it prioritizes high-fat and protein-rich foods that’ll give you the meat sweats just reading about them. For breakfast, ChatGPT suggested meals like scrambled eggs with spinach, bacon, and avocado, or Greek yogurt with nuts and berries. Some kind of animal protein and greens, like zucchini noodles with meatballs, were typical for lunch and dinner.
• What’s good? “This meal plan contains a lot less red meat than I would have expected,” says Nielsen. Keto diets tend to be light on vegetables, because of their carb content, but this one makes some effort to include produce at every meal. However, says Nielsen, someone who might medically need to follow this meal plan “can’t be sure that the balance of fat, protein, and carbohydrate is actually adequate to achieve ketosis,” a metabolic state in which your body burns fat instead of sugar. 
• What’s not so good? Beyond treating legitimate but few medical conditions, such as nonresponsive epilepsy, most dietitians don’t recommend a keto diet. It’s “deeply restrictive,” could exacerbate eating disorders, and sets people up for “sky-high cholesterol levels and nutrient deficiencies.” says Nielsen. It’s also super low in fiber, which can cause constipation. Because ketosis tends to decrease sodium in the body, “people on a long-term keto diet also need to increase their sodium intake, which is super dangerous to do if you are not sure you’re in ketogenic metabolism, and super dangerous not to do if you are,” she adds.
• Final grade: C

Vegan 

• Overview: According to ChatGPT, “a vegan diet is one that eliminates all animal products, including meat, dairy, eggs, and honey.” The kinda bland seven-day meal plan suggested I eat vegan yogurt with fruit and granola for breakfast; hummus and a vegetable wrap with baby carrots for lunch; and vegan shepherd’s pie for dinner.
• What’s good? “AI knows legumes exist!” says Nielsen. The plan includes some sort of bean or lentil for lunch or dinner, which are a great source of fiber, vitamins and minerals, and vegan protein.  
• What’s not so good? That said, “the breakfast meals appear consistently low in protein, which might leave the person feeling hungry—especially without a snack,” says Moore. She notes the plan is also low in essential vitamins and minerals, such as omega-3 fatty acids, B12, zinc, iron, and calcium. Nielsen agrees, adding that “some of these days don’t seem like a lot of food.”
• Final grade: B-

Intermittent Fasting

• Overview: This diet, designed specifically for weight loss, typically involves not eating for about 16 hours and then smashing a day’s worth of food in eight hours. For this seven-day plan, ChatGPT not only suggested three meals and two snacks per day, but also the times which people should eat them—spanning from noon until 8 p.m. Follow this plan and you’d be eating avocado toast with a poached egg for “breakfast” at noon, grilled chicken with roasted vegetables for lunch at 4 p.m., and salmon with quinoa for dinner at 8 p.m. 
• What’s good? “It is making an effort to get fruits and vegetables into almost every meal and snack, which, for the average American, is more than they’re currently eating,” says Nielsen. “Honestly, if this was a client’s food record—minus the time restricted eating—I would say that it’s clear they are making efforts to eat a balanced whole food diet. Gold star, robot!”
• What’s not so good? That said, intermittent fasting can be dangerous for menstruating adults and people with a history of disordered eating—the latter of “which will be many of the same people who are searching for this very meal plan,” says Nielsen. “Ignoring your natural hunger cues in order to fit the eight-hour eating window can be deeply harmful to your relationship with food and your body. Plus, it may be physically harmful depending on your preexisting conditions, such as diabetes.” (Fasting for long periods can cause insulin levels to spike and drop.)
• Final grade: B+ 

Mediterranean Diet 

• Overview: There are no real rules around the Mediterranean diet, but the general vibe is to eat whole grains, plants, and good-for-your-heart fats like olive oil. It’s inherently a diet with a lot of options and few restrictions. With the spotlight on ingredients like feta cheese and pasta and pita bread, ChatGPT’s plan for this one actually looks delicious and not too dissimilar from what I eat in a regular week (minus the meat). ChatGPT suggested toast with avocado and poached eggs for breakfast; falafel salad with mixed greens, tomatoes, cucumber, and tahini for lunch; baked salmon with roasted veg for dinner; and “apple slices with almond butter” or a non-prescriptive “handful of almonds” for snacks. 
• What’s good? “This meal plan offers plenty of fruits and vegetables without neglecting nuts or legumes,” says Nielsen, who would “green-light” most of the meals for her clients. “This diet is very noncontroversial and well researched, so it makes sense that ChatGPT knocked this one out of the park.” 
• What’s not so good? That said, it might not be a great option as is for vegans or vegetarians. “I would have liked to see more legumes, as I am wondering what [this group] would do for protein. It’s also deeply Eurocentric and not right for everyone in terms of cultural eating,” says Nielsen.
• Final grade: A-