What Are Ultra-Processed Foods—and Why Avoid Them?
Ultra-processed foods now make up nearly 60% of calories in the average American diet. A growing body of research links them to heart disease, diabetes, obesity, and early death. Here's what they are, why they're everywhere, and what the science says.
What the NOVA System Tells Us
Not all processed food is equal. Scientists at the University of São Paulo developed the NOVA classification system, which divides all foods into four groups based on how extensively they have been industrially altered. At the top — Group 4 — sit ultra-processed foods: ready-to-eat or ready-to-heat products formulated from industrial ingredients, artificial flavors, emulsifiers, colorings, and preservatives, often with little resemblance to any whole food.
Think soft drinks, flavored chips, packaged cookies, instant noodles, hot dogs, sweetened breakfast cereals, and most frozen ready meals. The defining feature is not just what has been added — sugar, salt, fat — but what these products are: chemical formulations engineered for palatability, long shelf life, and convenience, rather than nutrition.
Why Ultra-Processed Foods Are Everywhere
Ultra-processed foods now account for nearly 60% of daily calorie intake among American adults and close to 70% among children, according to Yale Medicine. In the UK and many European countries, the figures are similar. The reasons are straightforward: they are cheap to produce, require minimal preparation, have long shelf lives, and are intensely marketed. Food companies invest heavily in optimizing their taste profile — the precise combination of salt, fat, sugar, and texture that keeps consumers eating more than intended.
The Health Toll
A growing body of evidence links high ultra-processed food consumption to a wide range of diseases. A 2026 study published in The American Journal of Medicine found that people with the highest intake of ultra-processed foods faced a 47% higher risk of heart attack and stroke compared to those who ate the least. Earlier research published in The Lancet Regional Health found each additional 100 grams per day of ultra-processed food was associated with a 14.5% higher risk of hypertension and a 5.9% increase in cardiovascular events.
The risks extend well beyond the heart. An umbrella review covering dozens of meta-analyses and nearly 10 million study participants found convincing associations between ultra-processed food consumption and 32 different adverse health outcomes — including a 55% higher risk of obesity, a 40% higher risk of type 2 diabetes, a 48% higher anxiety risk, and a 21% higher risk of early death from any cause.
Why Are They So Harmful?
Researchers point to several overlapping mechanisms. Ultra-processed foods are typically calorie-dense but nutrient-poor: they deliver excess sugar, saturated fat, and sodium while providing little fiber, vitamins, or phytochemicals. But many scientists argue that the additives themselves also play a role. Certain emulsifiers — such as carboxymethylcellulose and polysorbate-80 — have been shown in animal studies to disrupt the gut microbiome and promote low-grade inflammation. Artificial sweeteners may alter insulin response and gut bacteria. The high glycemic load of many ultra-processed foods drives blood sugar spikes and long-term metabolic damage.
There is also a behavioral dimension. These products are specifically engineered to override the body's natural satiety signals, making it easy to consume far more calories than intended — a phenomenon researchers call hyperpalatability. As Stanford Medicine notes, the combination of industrial additives and optimized taste profiles can make these foods functionally habit-forming.
What the Research Cannot Yet Prove
Most studies on ultra-processed foods are observational: they identify associations, not direct causation. People who eat large amounts of ultra-processed foods may also have lower incomes, less access to fresh food, higher stress levels, or less time to cook — all of which independently affect health. Researchers acknowledge this limitation, and randomized controlled trials directly testing ultra-processed diets in humans remain relatively few. That said, the sheer volume and consistency of the evidence — across different countries, populations, and study designs — has led many nutrition scientists and organizations, including the American College of Cardiology, to call for policy action.
What You Can Do
The simplest practical guidance from nutritionists is to focus on whole or minimally processed foods: fruits, vegetables, legumes, whole grains, fish, eggs, and dairy. Reading ingredient labels helps: if a product contains a long list of additives — emulsifiers, artificial flavors, colorings, stabilizers — it is likely ultra-processed. Cooking from scratch, even occasionally, dramatically reduces exposure. Some countries, including Brazil and France, have begun updating official dietary guidelines to explicitly warn against ultra-processed foods rather than focusing only on individual nutrients like fat or sugar.
The science is still evolving, but the direction of evidence is clear: the more ultra-processed food dominates a diet, the greater the health risk — across the heart, metabolism, gut, and even mental health.
