Walking through the aisles of any grocery store, you cannot help but come across items such as packaged snacks, convenient pre-prepared meals, sodas, and sweetened breakfast cereals. These food products generally fall under the category of ultra-processed foods (UPFs), which are linked to some of the most prevalent chronic diseases today. Today, ultra-processed foods account for more than 50 percent of caloric intake in many countries.
This was not done without reason. Manufacturers are highly motivated to develop products that are cheap to make, have an extended shelf life, and are designed to be incredibly delicious, often at the expense of nutritional value. In this guide, we will cover what ultra-processed foods are, how they differ from other types of processed foods, and what the current research, including work from the scientists who defined this category, has to say about it.
What Are Ultra-Processed Foods?
UPFs are industrially formulated products made mainly from food constituents that have been isolated or chemically modified, combined with additives used to enhance flavor, color, texture, and shelf stability. They usually contain ingredients not found in a home kitchen pantry.
The NOVA Classification System and the Scientist Behind It
The term "ultra-processed food" and the classification system used to define it were introduced in 2009 by Dr. Carlos A. Monteiro, an epidemiologist and Emeritus Professor of Nutrition and Public Health at the University of São Paulo, Brazil, along with colleagues at the university's Center for Epidemiological Research in Nutrition and Health.¹ Monteiro and his co-authors, including Geoffrey Cannon, Jean-Claude Moubarac, and Renata Bertazzi Levy, formally outlined the resulting NOVA classification system in a widely cited 2018 paper in Public Health Nutrition.² Monteiro has since served on the WHO Expert Advisory Board on Nutrition Issues.
NOVA groups foods into four categories based on how they are processed:
Unprocessed or minimally processed foods such as fruits, vegetables, eggs, plain meats, cereals
Processed culinary ingredients such as oils, butter, sugar, salt
Processed foods such as canned vegetables, cheese, freshly baked bread
Ultra-processed foods such as packaged snacks, soft drinks, instant noodles, frozen ready meals, sweetened cereals
However, the important distinction is not simply the amount of processing, but the purpose behind it. UPFs are formulated for convenience, shelf stability, and taste, sometimes using recipes engineered to be highly palatable. What sets them apart from traditionally processed foods, such as dried or fermented foods, is their reliance on industrially derived ingredients and additives.
Why Are Ultra-Processed Foods So Dominant?
Three main factors explain their dominance: they tend to be cheaper than whole foods on a per-calorie basis, they require little to no preparation, and they are formulated to hit an ideal combination of salt, sugar, and fat, often called the "bliss point."
Common Examples of Ultra-Processed Foods
Carbonated soft drinks and sweetened juices
Packaged chips, biscuits, and cookies
Instant noodles and packaged macaroni and cheese
Frozen pizzas and ready-to-heat meals
Processed meat products like hot dogs and chicken nuggets
Sweetened breakfast cereals and flavored yogurts
Chocolates, ice cream, and commercially baked cakes
The Impact of Ultra-Processed Foods on Your Wellbeing
A growing body of research links high UPF consumption to a range of negative health outcomes. Here is what some of the leading studies and the researchers behind them have found.
1. Excessive Weight Gain and Obesity
The strongest causal evidence on this point comes from Dr. Kevin D. Hall, a senior investigator at the U.S. National Institutes of Health's National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). In a 2019 randomized controlled trial published in Cell Metabolism, Hall and colleagues admitted 20 adults to the NIH Clinical Center for one month, feeding them ultra-processed and minimally processed diets matched for calories, sugar, fat, sodium, and fiber for two weeks each, in random order.³ Participants were free to eat as much or as little as they wanted. On the ultra-processed diet, they consumed roughly 500 more calories per day and gained an average of 0.9 kg (about 2 lbs) over two weeks, despite reporting the meals as equally pleasant.³ "This is the first study to demonstrate causality that ultra-processed foods cause people to eat too many calories and gain weight," Hall said at the time.⁴ Researchers believe factors like softer texture, higher energy density, and faster eating speed help explain the effect, though the exact mechanisms are still being studied.
2. Higher Risk of Chronic Disease
In 2024, Melissa M. Lane and colleagues at Deakin University's Food & Mood Centre published a large umbrella review in The BMJ, pooling data from 14 existing meta-analyses covering nearly 10 million participants.⁵ The review found that higher UPF consumption was consistently associated with an increased risk of:
Type 2 diabetes
Cardiovascular disease and related mortality
Certain cancers
Common mental disorders such as anxiety and depression
Overweight and obesity
All-cause mortality
Lane and colleagues reported that greater UPF exposure was associated with a higher risk across roughly 71% of the 45 health outcomes examined.⁵ The authors note this evidence is observational, showing a consistent association rather than definitive proof of a direct causal pathway for every outcome, but the scale and consistency of the findings led the researchers to recommend public health measures to reduce UPF consumption.
3. Poor Metabolic and Gut Health
Processed foods tend to be low in fiber but high in refined carbohydrates, added sugar, and unhealthy fats. Emulsifiers and other additives common in these products are also being studied for their potential to disrupt the gut microbiome, an active area of research in nutrition science.
4. Effects on Mental Wellbeing and Cognition
The Lane et al. BMJ review noted above found consistent associations between UPF intake and a higher risk of common mental disorders, including depression and anxiety.⁵ Researchers caution that it remains unclear whether this reflects a direct biological effect, a broader pattern of unhealthy lifestyle habits, or some combination of both.
5. Nutrient Displacement
Because UPFs are calorie-dense but nutrient-poor, diets that include excessive amounts of these products tend to "crowd out" whole foods rich in fiber, vitamins, minerals, and protein. Added sugar is a particularly common culprit in UPFs. If you're curious how sugar itself affects the brain's reward system, see our related guide on whether sugar is actually addictive.
Processed vs. Ultra-Processed: What's the Difference?
Not all processing is bad. A bag of frozen vegetables, canned beans, or whole-grain bread is technically "processed" but remains highly nutritious and minimally altered. The concern lies specifically with ultra-processed foods, which undergo significant industrial transformation and contain additives not typically used in home cooking, such as hydrogenated oils, protein isolates, artificial sweeteners, and flavor enhancers.
A simple rule of thumb: if the ingredient list is long and includes items you wouldn't keep in your own pantry, it's likely ultra-processed. Many UPFs also rely heavily on refined vegetable and seed oils for texture and shelf life. For a deeper look at that ingredient specifically, see our guide on seed oils and your health.
Ultra-Processed Foods and Children's Health
Children are often the heaviest consumers of UPFs, since these products frequently dominate the caloric content of school meals, packaged children's snacks, and kid-marketed foods. Early, frequent exposure to intensely sweet or salty flavors may make it harder to develop a taste for whole foods later on. Pediatric health researchers increasingly point to high UPF consumption in childhood as a contributing factor in rising rates of childhood obesity and early-onset metabolic issues.
Practical Tips to Reduce Ultra-Processed Foods in Your Diet
You don't need to eliminate UPFs to see health benefits; small, sustainable changes make a real difference.
Start With Simple Swaps
Replace soda with sparkling water and fresh fruit
Choose plain yogurt with fresh fruit instead of flavored, sweetened varieties
Swap packaged snack bars for nuts, seeds, or fruit
Cook simple meals at home using whole ingredients a few times a week
Read Ingredient Labels
Choose foods with short, recognizable ingredient lists. A long list of unfamiliar additives is a strong signal that a food is ultra-processed.
Plan and Batch-Cook
Preparing meals in advance reduces reliance on convenience foods during busy weekdays, making whole-food choices easier to stick to.
Frequently Asked Questions
Are all processed foods bad for you?
No. Many processed foods, such as canned beans, frozen vegetables, and whole-grain bread, retain most of their nutritional value. The health concerns identified by researchers like Monteiro and Lane are specifically associated with ultra-processed foods.
Can I eat ultra-processed foods occasionally?
Yes. Occasional consumption within an otherwise balanced, whole-food-based diet is unlikely to cause significant harm. The elevated risks identified in studies like the 2024 BMJ umbrella review are associated with diets where UPFs make up a large share of daily calories.
How can I tell if a food is ultra-processed?
Check the ingredient label. Ultra-processed foods typically contain ingredients not used in home cooking, such as high-fructose corn syrup, hydrogenated oils, protein isolates, emulsifiers, and artificial flavors or colors.
Is a "diet" or low-calorie version of a food automatically healthier?
Not necessarily. Many reduced-calorie products are still ultra-processed, relying on artificial sweeteners and thickeners to mimic the taste and texture of the full-calorie version.
Key Points
Ultra-processed foods now make up a substantial share of daily calorie intake in many countries. Foundational research from Carlos Monteiro's original NOVA classification, to Kevin Hall's controlled feeding trial showing UPFs directly cause overeating, to Melissa Lane and colleagues' large-scale 2024 review linking UPFs to over 30 adverse health outcomes has built a consistent picture linking high UPF consumption to obesity, metabolic disease, and other chronic conditions.
The goal isn't perfection; very few people eat a diet completely free of ultra-processed foods, and that's not necessary for good health. What matters most is the overall pattern: building meals around whole or minimally processed ingredients most of the time, while treating heavily processed foods as the exception rather than the rule.
Sources & Research Cited
Monteiro, C. A., Cannon, G., Levy, R. B., et al. "Ultra-processed foods: what they are and how to identify them." Public Health Nutrition, 22(5), 936–941 (2019). PubMed: 30744710
Monteiro, C. A., Cannon, G., Moubarac, J. C., Levy, R. B., Louzada, M. L. C., Jaime, P. C. "The UN Decade of Nutrition, the NOVA food classification and the trouble with ultra-processing." Public Health Nutrition, 21(1), 5–17 (2018). PubMed: 28322183
Hall, K. D., Ayuketah, A., Brychta, R., et al. "Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake." Cell Metabolism, 30(1), 67–77 (2019). PubMed: 31105044
National Institutes of Health. "NIH study finds heavily processed foods cause overeating and weight gain." NIH News Release, May 16, 2019. nih.gov
Lane, M. M., Gamage, E., Du, S., et al. "Ultra-processed food exposure and adverse health outcomes: umbrella review of epidemiological meta-analyses." The BMJ, 384:e077310 (2024). DOI: 10.1136/bmj-2023-077310
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