AI apps that count calories from a photo: are they accurate? What a 2026 study found
Snap your plate and the app tells you the calories. A study presented in 2026 found they undercount by 250 to 345 kcal per meal. How to use them well and when not to trust them.
It’s one of the most popular AI features right now: take a photo of your plate and the app estimates the calories and nutrients. MyFitnessPal, Lose It!, Cal AI and many others offer it. But are they accurate?
⚕️ Health note: this article is for information only. If you have diabetes, an eating disorder or any health condition, talk to your doctor or a registered dietitian before changing your diet.
What the science says
In 2026, a team of researchers presented a very clear study at NUTRITION 2026:
- They photographed 102 meals weighed to the gram.
- They ran them through four apps: MyFitnessPal, Lose It!, Cal AI and Appediet.
- All four undercounted: on average they estimated 250 to 345 fewer calories than the real amount per meal, and about 30 grams less fat.
- They were more consistent with carbohydrates than with other nutrients.
- Interestingly, they missed by more on lighter meals than on very high-calorie ones.
In practical terms: if you eat three meals a day and trust the app blindly, you could be eating around 800 calories more than you think.
Why do they get it wrong?
- Portions. A photo can’t tell 100 grams of rice from 200. That’s the main source of error.
- What you can’t see. Oil, butter, sauces, sugar in your coffee.
- Mixed dishes. A stew or a lasagna is hard to break down.
- Local food. Many apps are trained mostly on certain cuisines and struggle with others.
How to use them well
- ✅ Always correct the portion size the app suggests. The study explicitly recommends it.
- ✅ Add oil and sauces manually.
- ✅ Weigh your food for the first few weeks to learn to eyeball it.
- ✅ Use them to spot trends, like eating more vegetables or fewer ultra-processed foods, rather than counting every calorie.
- ✅ Shoot from above, in good light, with something for scale, like a fork.
When not to trust them
- ❌ If you need medical precision: insulin-dependent diabetes, kidney disease or a prescribed diet.
- ❌ If counting calories causes you anxiety or guilt. In that case, stop and talk to a professional.
- ❌ For children: calorie-counting diets aren’t recommended without supervision.
What about ChatGPT or Gemini?
You can also upload a photo of your plate to a chatbot and ask. They have the same portion problems, and they can also make up figures with total confidence. We explain it in AI hallucinations. Where they really shine is planning: menus, recipes and grocery lists. See meal planning with AI.
In short
Photo apps are convenient and motivating, but they’re not a kitchen scale. Use them as a guide, correct the quantities and don’t make health decisions based on them alone.
