Researchers watched what people bought at Canadian supermarkets before and after stores added a special labeling system called Guiding Stars® that shows which foods are healthier. They tracked nearly 1.88 billion products sold across three major supermarket chains. The study found that the labels did help—people bought slightly more fresh and lightly processed foods and fewer ultra-processed foods like packaged snacks and frozen meals. However, the effect was small and worked better for some food types than others. The findings suggest that putting nutrition labels on store shelves can nudge shoppers toward better choices, especially if the labels also consider how much the food has been processed.

The Quick Take

  • What they studied: Whether a store labeling system that rates food healthiness (Guiding Stars®) actually changes what people buy, and whether it helps people avoid ultra-processed foods
  • Who participated: Shoppers at three major Canadian supermarket chains who made nearly 1.88 billion purchases. The study compared what people bought before and after the labeling system was introduced, with some stores getting the labels and others not
  • Key finding: The labeling system caused small but real increases in purchases of fresh and minimally processed foods, with an overall trend away from ultra-processed foods. However, the effect varied by food type—some categories showed bigger changes than others
  • What it means for you: Store nutrition labels may help you make healthier choices without requiring much effort on your part. The effect is modest, so labels work best when combined with other healthy eating strategies. The impact depends on which foods you’re shopping for

The Research Details

This was a before-and-after study that looked at real shopping data from Canadian supermarkets. Researchers compared what people bought in stores that added the Guiding Stars® labeling system to stores that didn’t have the system. They examined about 61,456 different food and drink products to see how they were labeled and tracked sales of nearly 1.88 billion items over time.

The researchers used two different classification systems to organize foods. The Guiding Stars® system rates foods based on their nutritional content (like sodium, sugar, and fat). The NOVA system categorizes foods based on how much they’ve been processed—from fresh fruits and vegetables to ultra-processed foods like packaged snacks and instant meals. By comparing these two systems, researchers could see if the nutrition labels aligned with how processed the foods were.

The study measured changes in sales by counting how many units of each type of food were sold before and after the labels were introduced. This allowed them to see if people actually bought different foods when the labels were available.

This research approach is important because it uses real shopping data rather than just asking people what they think they’ll buy. When researchers track actual purchases, they get honest information about how people really behave in stores. The large sample size—nearly 1.88 billion products sold—makes the findings more reliable and representative of what happens in real supermarkets. By comparing stores with labels to stores without labels, researchers could see the true effect of the labeling system rather than other factors that might influence shopping habits.

This study has several strengths: it uses real transaction data from actual supermarkets rather than surveys, it includes a very large number of purchases making results more reliable, and it compares labeled stores to unlabeled stores to show the true effect. However, the study was conducted in Canada and may not apply exactly the same way in other countries. The researchers couldn’t control for all factors that might influence shopping, such as price changes or advertising. The changes observed were small, which means the labeling system alone isn’t a complete solution for healthier eating.

What the Results Show

The study found that the Guiding Stars® labeling system and the NOVA food processing classification system agreed moderately well on which foods were healthier. This means the labels were generally pointing people toward foods that were also less processed.

When stores added the Guiding Stars® labels, shopping patterns shifted slightly but noticeably. People bought more fresh and minimally processed foods in three food categories and more moderately processed foods in three other categories. At the same time, purchases of ultra-processed foods decreased relative to these healthier options. Ultra-processed foods still made up the majority of what people bought (53.7%), but the trend was moving in a healthier direction.

However, the effect wasn’t consistent across all food types. In some categories, people actually bought more ultra-processed foods even after the labels were added. This suggests that labels work better for some types of foods than others—perhaps because people have stronger habits with certain foods or because the price differences between healthy and unhealthy options vary by category.

Overall, the researchers found that on-shelf nutrition labels can influence shopping behavior, but the effect is modest. The changes were statistically significant (meaning they’re real and not due to chance), but they were small in practical terms.

The study revealed that the Guiding Stars® system and NOVA classification had moderate agreement but weren’t perfect matches. This means some foods that the nutrition label rated as healthy were still quite processed, and vice versa. This finding suggests that combining nutrition information with processing level information might help labels work even better. The research also showed that different food categories responded differently to the labels—some shoppers changed their behavior more in certain aisles than others, suggesting that labeling strategies might need to be tailored by food type.

This research adds to growing evidence that on-shelf nutrition labels can influence shopping choices. Previous studies have suggested labels help, but this study is notable because it uses actual sales data from a real supermarket chain rather than laboratory studies or surveys. The finding that labels have a modest effect aligns with other research showing that while labels help, they’re not a complete solution by themselves. The study’s focus on food processing is relatively newer—most previous research focused mainly on nutrients like fat and sugar rather than how processed foods are.

The study was conducted only in Canada, so results may differ in other countries with different food cultures and shopping habits. The researchers couldn’t control for everything that might affect shopping—for example, if prices changed or if stores ran special promotions, that could influence buying patterns beyond just the labels. The changes observed were small, so while they’re real and statistically significant, they don’t represent a dramatic shift in shopping behavior. The study looked at overall trends but couldn’t track individual shoppers to see who was most influenced by the labels. Additionally, the study couldn’t determine if people actually read and understood the labels or if they simply noticed them and made unconscious choices.

The Bottom Line

Based on this research, store nutrition labels appear to help people make slightly healthier choices (moderate confidence level). The effect is small but real. Labels work best when combined with other strategies like education about healthy eating, affordable pricing for nutritious foods, and personal motivation. If you’re trying to eat healthier, use the labels as one tool among many—they can help guide your choices, but they work best alongside other healthy habits.

Everyone who shops for groceries can benefit from understanding nutrition labels, though the effect is modest. People trying to reduce ultra-processed foods in their diet may find labels particularly helpful. Parents shopping for their families might find labels especially useful for making quick, healthier choices. However, people shouldn’t rely on labels alone—they work best as part of a broader healthy eating approach. The study suggests labels may work better for some food categories than others, so you might notice more impact in certain aisles.

You probably won’t notice dramatic changes immediately. The study showed small shifts in shopping patterns, so expect gradual changes over weeks to months rather than overnight transformations. If you actively use the labels to guide your choices, you might see more noticeable changes in your diet than the average shopper. The real benefit comes from consistently using the labels over time as part of your regular shopping routine.

Want to Apply This Research?

  • Track the number of ultra-processed foods versus fresh/minimally processed foods in your weekly shopping cart. Count items in each category and aim to gradually increase the percentage of fresh foods. For example, track: ‘This week I bought 8 ultra-processed items and 12 fresh/minimally processed items’ and work toward a 40/60 or 30/70 ratio over several weeks
  • When shopping, use the app to scan products and see their Guiding Stars® rating or processing level before adding them to your cart. Set a weekly goal like ‘Buy at least 3 new fresh or minimally processed foods this week’ and log them in the app. Use the app’s reminder feature to check labels before checkout
  • Track your shopping habits weekly by logging the types of foods you purchase. Create a simple chart showing the percentage of ultra-processed versus fresh foods over 4-8 weeks. Note which food categories are easiest for you to switch to healthier options and which are hardest. Use this information to set personalized goals for the categories where you struggle most

This research shows that store nutrition labels can help guide shopping choices, but the effect is modest and varies by food type. Labels should not be your only tool for healthy eating—they work best combined with overall healthy lifestyle habits, medical advice, and personal nutrition goals. If you have specific dietary needs or health conditions, consult with a healthcare provider or registered dietitian before making major changes to your diet. This study was conducted in Canada and results may vary in other regions. The findings represent trends in shopping behavior, not personalized nutritional advice.