Health risk of ultra processed foods

Ultra-processed foods are associated with higher risks of obesity and chronic diseases. This article summarises current evidence on the potential health harms linked to UPFs.

This article is from the Nutrition section of our Library.

About This Series

This is Article 3 of a 4-part series exploring ultra-processed foods: what they are, how they came into existence, how they affect your health, and how to stop eating them.

Previous articles covered what ultra-processed foods are and why they became widespread. This article examines what research reveals about their health effects.

As UPF consumption increased globally, researchers began investigating potential health concerns associated with it. Over the past decade, evidence has accumulated from around the world.

The findings have been consistent enough to attract attention from public health organisations and start debates about regulations and dietary guidelines.

Why Now?

For decades, nutrition research focused primarily on nutrients: fat, protein, carbohydrates, vitamins, and minerals. It was assumed that the health effects of food depend solely on what they are made of.

However, researchers observed that people who consumed similar amounts of calories and nutrients had different health outcomes and body weights.

They also noted that people would eat more of certain foods compared to others, even if they had the same amount of calories and nutrients.

So rather than focusing on just the content of the food, scientists started looking at the structure and processing methods used in different food products. This opened UPFs to scrutiny, as researchers found that people who eat a lot of UPFs tended to have poorer health prospects.

Weight and Obesity

The relationship between UPF consumption and body weight has received a lot of attention. Many studies find a consistent link between higher UPF intake and increased risk of overweight and obesity.

This link is consistent across people of different ages and across different countries. The more UPFs that are consumed, the fatter you're likely to be.

Experimental studies have shown that when people are offered UPFs, they tend to consume more of them, about 500 kcal a day more, and gain weight.

Cardiometabolic Disease

Research consistently links higher UPF intake to increased risk of cardiovascular disease, type 2 diabetes, high blood pressure, high cholesterol and high blood sugar levels. Even those with normal body weights are still at greater risk of cardiometabolic disease with higher UPF intakes.

Cancer

Some studies report associations between UPF consumption and certain cancers, particularly breast, colorectal, pancreatic and gastrointestinal cancers. Just a 10% increase in the proportion of UPFs in your diet is linked to higher cancer risk — that’s equivalent to a small UPF snack a day.

Mental Health

A recent study has linked consistent associations between higher UPF intake and increased risk of depression and anxiety. This is thought to be due to increased inflammation, changes in the microbiome, and/or fluctuating blood sugar levels.

How ultra-processed foods affect your health?

Energy Density and Calorie Intake

UPFs typically pack many calories into small volumes — they are “energy dense”. This high energy density makes consuming more calories easier — you can eat more calories before feeling full.

Even when two foods have the same nutritional content: same calories, fat, carbohydrate, salt, and sugar, people tend to eat more of the UPF than the minimally processed alternative.

Eating Rate and Food Structure

UPFs often have soft textures, which need minimal chewing. This allows faster eating, which is associated with consuming more calories.

The food structure matters as well as the nutrient content. Chewing whole foods slows eating and may trigger feelings of fullness more effectively. Processing breaks down food structure, making calories and nutrients more readily available, but potentially speeding up your natural eating pace.

“Hyperpalatability” and Reward

UPFs are designed to be highly palatable through specific combinations of fat, sugar, salt, and other strong flavourings. While there’s nothing wrong with foods tasting good, certain combinations may affect brain reward pathways in ways that encourage you to eat more of them.

The brain's reward system is hardwired to encourage us to eat energy-dense foods, which were scarce throughout most of human history. UPFs might stimulate these pathways more intensely than minimally processed alternatives.

Satiety and Hunger Signals

Eating food affects our feeling of fullness in a few ways: stomach expansion, sensing nutrients in the gut, hormonal release, and blood sugar patterns. UPFs may interact differently with these systems compared to whole foods.

Some UPFs are digested rapidly, causing quick rises and falls in blood sugar that can trigger renewed hunger and cravings. Other UPFs may not trigger satiety hormones as effectively as whole foods, even when providing equivalent calories.

Your Microbiome

The gut microbiome influences many other systems around the body: your metabolism, inflammation, and potentially even mood and behaviour. Some studies suggest that emulsifiers and other additives common in UPFs may negatively affect your gut and the bacteria in it.

Displacement of Nutritious Foods

A simpler, but overlooked cause, also deserves a mention. If UPFs take up a large portion of your diet, they replace other (healthier) foods. Even if UPFs weren’t harmful by themselves, if they replace fruits, vegetables, legumes, and other whole foods, this means you’ll miss the beneficial nutrients contained within them.

A Balanced Perspective

The evidence linking UPFs to various health outcomes has accumulated substantially over the past decade. However, there are still questions that remain unanswered.

Which UPFs or processing methods are influencing health? Do UPFs interact with other dietary, lifestyle, or personal circumstances? Is there a “safe” amount of UPF intake? Can exercise offset UPF intake? Can a better diet counteract UPF intake?

The research will continue. Guidelines and regulations may evolve (as they have already in many countries). But in the meantime, the evidence suggests that keeping UPF intake to a minimum, where practical, and in most cases, replacing them with whole foods, is advisable.

This doesn't necessarily mean eliminating all UPFs or feeling guilty about realistic food choices. It does suggest that reducing reliance on these products, when feasible, likely supports better health prospects.

Next in this series: Some practical Ways to reduce UPF Intake.