According to Gram Research analysis of a 2024 online randomized trial of 4,107 Latino adults, front-of-package warning labels helped people identify ultra-processed foods. The identity warning ‘WARNING: Ultra-processed food’ led 70% of participants to identify products correctly, compared with 54% who saw a standard barcode.
Ultra-processed foods are packaged products made with many industrial ingredients, and they are linked to chronic diseases such as obesity and type 2 diabetes. A 2024 online study of 4,107 Latino adults in the United States tested whether front-of-package warning labels could help people recognize these foods. According to research reviewed by Gram, labels that said ‘WARNING: Ultra-processed food’ or warned about weight gain and diabetes helped people identify these products more accurately than a standard barcode label. The warnings also made products seem less healthy and lowered people’s interest in buying them. The results were published in 2026 in the American Journal of Preventive Medicine. The study was online and involved only a set of four products, so the findings may not match what happens in a real grocery store.
Key Statistics
A 2026 randomized trial of 4,107 Latino adults published in the American Journal of Preventive Medicine found that the identity warning ‘WARNING: Ultra-processed food’ helped 70% of participants correctly identify ultra-processed products, compared with 54% who saw a standard barcode.
In the same 2024 online study, the health warning label about weight gain and type 2 diabetes helped 67% of Latino adults correctly identify ultra-processed foods, and both warning types made products seem less healthy to participants.
Participants who saw either warning label were significantly less likely to say they would buy the products they viewed than participants who saw a standard barcode, according to the 2026 randomized trial published in the American Journal of Preventive Medicine.
The Quick Take
- What they studied: The researchers wanted to know whether warning labels on the front of food packages could help people tell which foods are ultra-processed, and whether those labels changed how healthy people thought the food was and whether they wanted to buy it.
- Who participated: 4,107 Latino adults in the United States took part online. About half (49%) had limited English proficiency, meaning they do not speak or read English well. Each person was randomly assigned to see one of three label types.
- Key finding: When shown a warning label, 70% of people correctly identified the product as ultra-processed with the identity warning, and 67% did so with the health warning. Only 54% did so with a standard barcode label. Both warnings also made products seem less healthy and lowered interest in buying them.
- What it means for you: Warning labels may help people notice ultra-processed foods and think twice before buying them. This is a single online study, so these labels should be seen as one possible tool, not a complete solution to healthy eating. Reading ingredient lists and choosing whole foods still matter.
The Research Details
This was a randomized controlled trial, which means that each participant was placed into one of three groups by chance. The groups were a control group, which saw a standard barcode, an identity warning group, and a health warning group. Random assignment helps make sure that differences between groups come from the labels and not from other factors, such as age or prior beliefs.
Each participant looked at four food products. Every product showed the label assigned to that person. Participants were asked whether they thought each product was ultra-processed. This was the main measure. They also rated how healthy the product seemed, how likely they were to buy it, and how well the label got its message across.
The study was done online in 2024 and was registered under the identifier NCT06296355. Registering a trial in advance makes it harder for researchers to change their goals after seeing the results.
A randomized design is one of the strongest ways to test whether something causes a change. Because people were assigned to labels by chance, the researchers can be more confident that the labels, rather than the people themselves, explain the differences in results. Including a control group also shows what happens when people see a basic label instead of a warning.
The study had a large sample of more than 4,000 people, and it included a group that is often underrepresented in nutrition research, Latino adults with limited English skills. It was registered before it was run and used a control group, which are signs of careful design. However, the study was conducted online and asked people to look at pictures of products, not to shop in a real store. Results from a lab-style or online setting may not fully match real purchasing decisions. The paper was published in a respected peer-reviewed journal.
What the Results Show
The main result was about how well people could recognize ultra-processed foods. Participants who saw the identity warning, which said ‘WARNING: Ultra-processed food,’ correctly identified these products 70% of the time. People who saw the health warning did so 67% of the time. In the control group, which saw only a barcode, the rate was 54%. Both warnings clearly improved accuracy compared with the barcode, and the difference was too large to be due to chance.
The identity warning worked somewhat better than the health warning. This suggests that simply naming a product as ultra-processed may be more effective at helping people recognize it than explaining the health risks. The difference between the two warnings was smaller than the gap between either warning and the barcode.
Both warnings also changed how people judged the products. Compared with the barcode, participants rated products as less healthy and said they were less likely to buy them. Both warnings also made people feel the label was more effective at communicating its message.
The effects differed for some groups. The health warning appeared to help people with more education recognize ultra-processed foods more than people with less education. It also seemed to help people with limited English skills more than those with strong English skills. These differences are interesting, but they should be confirmed by future research before being treated as firm conclusions.
Beyond recognizing ultra-processed foods, the warnings lowered how healthy people thought the products were and how much they wanted to buy them. These are important because a person’s thoughts about a product often come before their choices at the store. The warnings also seemed to make people more aware of the message, which may help labels persist in people’s minds over time. The study did not measure actual purchases, so it is not known how much these changes would affect real shopping.
Earlier research on food warning labels, including studies on sugar, salt, and fat warnings in Latin America, has found that clear warnings can help people choose healthier products. This study adds to that work by focusing on ultra-processed foods, a category that many people do not understand, and by including Latino adults who may face language barriers with nutrition information. Its findings fit with the idea that clear, simple labels can improve understanding.
The study took place online and used a limited number of products, so it does not show how people would react in an actual store with many competing items, prices, and brand loyalties. It measured intentions to buy rather than actual purchases, and intentions do not always lead to behavior. The study also did not track people over time, so it is unclear whether the effects would last. Finally, the researchers only tested one type of label design, so other designs may work differently.
The Bottom Line
Based on this randomized trial, warning labels that name a product as ultra-processed or explain its health risks appear to help people recognize these foods and feel less interested in buying them. Confidence in the finding that labels improve recognition is fairly high because the trial was randomized and large. Confidence that these labels will change real-world eating habits is more moderate, since the study did not measure actual purchases. Consumers can still benefit from checking ingredient lists and choosing whole or minimally processed foods.
Shoppers who want to make healthier choices, families looking for simple ways to spot ultra-processed foods, and health professionals who work with Latino communities may find these findings useful. Policymakers and food companies considering front-of-package labels may also find the results relevant. People who already read labels carefully may notice less change. This study does not replace medical advice for anyone managing a condition such as diabetes.
Changes in how people recognize foods may happen quickly once they start noticing warning labels, possibly within a single shopping trip. Longer-term changes in eating patterns, weight, or blood sugar would take months or years to show up and would require further research. Anyone trying to change their diet should expect gradual progress rather than immediate results.
Frequently Asked Questions
Do warning labels help people recognize ultra-processed foods?
Warning labels appear to help. In a 2024 randomized trial of 4,107 Latino adults, 70% of people who saw an identity warning correctly identified ultra-processed products, compared with 54% who saw a standard barcode.
What is the difference between an identity warning and a health warning on food labels?
An identity warning simply says the product is ultra-processed. A health warning explains that these foods can cause weight gain, obesity, and type 2 diabetes. In the study, the identity warning worked slightly better for recognition.
Do warning labels on food make people less likely to buy the product?
The study found that both warning types lowered participants’ interest in buying the products they viewed, and also made the products seem less healthy. However, the study was online and measured intentions, not actual purchases in stores.
How can I tell if a packaged food is ultra-processed?
Ultra-processed foods are industrial formulations made mostly from substances extracted from foods or synthesized, often with many additives. Check the ingredient list for long lists of additives, and look for warning labels that identify the product as ultra-processed.
Want to Apply This Research?
- Track the number of packaged products you buy each week and note how many have a warning label or are classified as ultra-processed. Aim to lower this count by a set amount, such as one or two products per week, and review your progress every Sunday.
- Before putting a packaged item in your cart, check the front label and the ingredient list. If the product is labeled as ultra-processed, look for a whole-food alternative, such as plain oats instead of sweetened cereal, or frozen vegetables instead of prepared side dishes.
- Over several months, log your weekly ultra-processed food purchases and review the trend each month. Add a simple check-in every few weeks asking how you feel about your choices and whether labels are influencing you. Share the trends with a healthcare provider if you are managing a chronic condition.
This article summarizes a single online randomized trial and is for general information only. It is not medical or nutrition advice. Findings about warning labels may not apply to every person or every shopping situation. If you have diabetes, obesity, or another health condition, talk with your doctor or a registered dietitian before making major changes to your diet.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.