Ultra-Processed Foods: What They Are and Why They Matter

What exactly is ultra-processed food?

The term "ultra-processed food" comes from the NOVA classification system, developed by researchers at the University of São Paulo in the 2010s. NOVA divides all food into four groups based on how much industrial processing has been applied. The Food Insight scanner on this site uses the same system to flag products at the barcode level.

Identifying characteristics of a NOVA 4 product include ingredients such as:

• Hydrolysed proteins
• Modified starches
• Hydrogenated or interesterified fats
• Maltodextrin, dextrose, lactose, or other industrial sugars
• Flavour enhancers (monosodium glutamate, disodium guanylate)
• Artificial sweeteners (acesulfame K, aspartame, sucralose)
• Emulsifiers (sunflower lecithin, mono- and diglycerides of fatty acids, carrageenan, polysorbates)
• Artificial colours
• Preservatives not typically used in home cooking (sodium benzoate, BHT, TBHQ)
• Bulking agents, thickeners, gelling agents

For more on the additive side, see our guide to food additives and E numbers.

Why NOVA Group 4 is different from "processed"

The word "processed" is often used loosely, and this causes confusion. Tinned tomatoes are processed. So is smoked salmon. So is cheddar cheese. But none of these are ultra-processed. The difference is not just the number of ingredients. It is the type of ingredients and the nature of the industrial process.

Ultra-processing typically involves:

1. Fractionation. Breaking whole foods down into their component parts (proteins, fats, starches, sugars) to use as raw materials.
2. Reconstitution. Reassembling those fractions into something that resembles food, with additives to achieve the desired texture, taste, and appearance.
3. Fortification. Adding back some of the vitamins and minerals that were removed during processing, often to satisfy regulatory labelling requirements.

The result is a product that may look, smell, and taste like food, but has a very different effect on the body from the whole food it was derived from.

How much UPF do people in the UK eat?

The UK has one of the highest rates of ultra-processed food consumption in Europe.

• UK adults get approximately 54% of their daily calories from NOVA 4 foods, according to data from the National Diet and Nutrition Survey (NDNS) covering 2008 to 2016.
• UK teenagers (aged 11 to 18) get approximately 66% of their daily calories from UPF, based on NDNS data from 2008/09 to 2018/19, analysed by researchers from Cambridge and Bristol (Chavez-Ugalde et al., European Journal of Nutrition, 2024).
• UPF consumption is highest among younger people, those with lower income, and those with lower levels of education. This reflects that ultra-processed foods are typically cheaper per calorie than whole foods and often more aggressively marketed.
• A 2024 study from the University of Liverpool found that 73% of UK adults were aware of the term "ultra-processed food", and 58% said UPF status influences their food choices, though most struggled to accurately identify specific products.

These figures matter because diet-related disease is already costing the UK economy enormously. A 2024 analysis by the Food, Farming and Countryside Commission estimated food-related chronic disease costs the UK around £268 billion per year, comparable to the entire NHS budget.

What the research says about UPF and health

The evidence linking high UPF consumption to poor health outcomes has grown substantially since 2020. The most comprehensive assessment to date is a 2024 umbrella review in the BMJ (Lane et al.), which pooled data from 45 meta-analyses covering close to 10 million people. Below is a summary of what the evidence shows, broken down by condition.

Obesity and weight gain

This is where the evidence is strongest. Multiple large studies have found a consistent association between UPF intake and higher body weight, higher BMI, and greater waist circumference.

A study using UK NDNS data (Rauber et al., 2020) found that UK adults in the highest quartile of UPF consumption had a BMI 1.66 kg/m² higher, a waist circumference 3.56 cm greater, and 90% higher odds of being obese compared to those in the lowest quartile.

A landmark randomised controlled trial at the NIH (Hall et al., Cell Metabolism, 2019), the most robust study design available, put participants on either an ultra-processed diet or an unprocessed diet for two weeks each, with both diets matched for total calories, sugar, fat, fibre, and macronutrients. Participants on the ultra-processed diet consumed an average of 500 kcal more per day and gained weight; those on the unprocessed diet lost weight.

A key suspected mechanism is that UPFs tend to be eaten faster (they require less chewing), delivering calories before the body's satiety signals have time to respond. The texture engineering that makes UPFs pleasant to eat also appears to reduce satiety compared to whole foods of equivalent caloric value.

Type 2 diabetes

The 2024 BMJ umbrella review classified the evidence linking UPF to type 2 diabetes as "highly suggestive". Multiple prospective cohort studies have found that people who eat the most UPF have a significantly higher risk of developing type 2 diabetes than those who eat the least.

Potential mechanisms include the high glycaemic load typical of UPFs, the disruption of gut microbiome composition by certain emulsifiers and artificial sweeteners, and the effect of obesity itself (which UPFs promote) as a major diabetes risk factor.

Cardiovascular disease and mortality

Higher UPF intake has been associated with increased risk of cardiovascular events (heart attack, stroke), cardiovascular mortality, and all-cause mortality.

A large UK Biobank analysis (covering data from 2006 to 2020) found significant associations between UPF consumption and both cardiovascular disease incidence and all-cause mortality in the UK population. The 2024 BMJ umbrella review classified cardiovascular mortality and cardiovascular events as having "suggestive" evidence of association with UPF consumption.

Cancer

The evidence is more varied for different cancer types, but the direction of association is consistently towards increased risk.

• Processed meats (NOVA 4) are classified as a Group 1 carcinogen by the World Health Organization's International Agency for Research on Cancer (IARC), the same category as tobacco and asbestos, based on sufficient evidence of a link to colorectal cancer.
• A 2023 analysis of UK Biobank data found associations between overall UPF consumption and increased risk of 34 types of cancer, with the strongest associations for ovarian and brain cancer.
• The 2024 BMJ umbrella review found "weak" evidence for colorectal cancer, colon cancer, and colorectal adenoma specifically from UPF consumption overall.

Mental health: depression and anxiety

The link between UPF and mental health is a newer but rapidly growing area of research.

The 2024 BMJ umbrella review classified the association between UPF and depression and common mental disorders as "highly suggestive". The association with anxiety was rated as "suggestive".

Possible mechanisms include the influence of UPF on gut microbiome composition (via emulsifiers and artificial sweeteners), chronic low-grade systemic inflammation (linked to both UPF and depression), and nutritional deficiencies. UPF diets tend to be low in fibre, omega-3 fatty acids, and micronutrients that play a role in brain function.

Gastrointestinal health

A 2024 umbrella review found "weak" evidence linking UPF consumption to inflammatory bowel disease and irritable bowel syndrome. The gut microbiome link is a plausible mechanism: certain additives commonly used in UPF, including the emulsifiers carboxymethylcellulose and polysorbate 80, have been shown in animal studies and some human studies to disrupt the mucus lining of the gut and alter the balance of gut bacteria.

Children and adolescents

The research on UPF and children is less extensive than the adult literature, but consistently points towards harm. The 2024 BMJ umbrella review found "highly suggestive" evidence for the association between UPF and obesity in children. Evidence also exists linking UPF to cardiometabolic risk factors and asthma in children and adolescents.

The UK's high rate of teenage UPF consumption, around two-thirds of daily calories, makes this a significant public health concern.

Biological ageing and frailty

A 2025 study using data from 172,225 UK Biobank participants (Wang et al., GeroScience) found that higher UPF consumption was associated with accelerated biological ageing as measured by a validated biomarker index (PhenoAge), and that this accelerated ageing partially mediated the increased all-cause mortality risk seen in high UPF consumers.

Why is ultra-processed food bad? The suspected mechanisms

Observational studies can show associations, but they cannot prove causation on their own. Researchers have proposed several plausible biological mechanisms that might explain why UPF causes harm. These mechanisms strengthen the case that the associations are real rather than coincidental.

1. Nutritional displacement. People who eat a lot of UPF eat fewer whole foods. As a result, their diet tends to be lower in fibre, protein, vitamins, minerals, and polyphenols. These deficiencies have their own established health consequences.
2. Hyperpalatability and overconsumption. UPFs are specifically engineered to be intensely pleasurable to eat, with combinations of fat, salt, sugar, and texture that are rarely found together in nature. This design drives overconsumption in a way that whole foods typically do not.
3. Disruption of gut microbiome. Emulsifiers, artificial sweeteners, and certain preservatives have been shown to alter gut microbiome composition in ways associated with inflammation, metabolic disruption, and increased gut permeability. A healthy gut microbiome is increasingly understood to be central to immune function, metabolic health, and mental wellbeing.
4. Endocrine disruption. Some additives and packaging materials associated with UPF (including certain plasticisers and food contact materials) may act as endocrine disruptors, interfering with hormonal signalling.
5. Advanced glycation end products (AGEs). The high-temperature industrial processing used to make many UPFs produces compounds called advanced glycation end products, which are associated with inflammation, diabetes complications, and ageing.
6. Contaminants from processing. Industrial refining, deodorising, and high-temperature extrusion can generate processing contaminants not found in the original whole food.
7. Eating speed and satiety signalling. The soft, uniform texture of many UPFs reduces the amount of chewing required, which shortens the mealtime and reduces the time available for satiety signals to reach the brain. This likely contributes to the overconsumption seen in experimental feeding studies.

The debate. Is the science settled?

It is important to be clear about where the science stands. The associations between UPF and poor health are consistent and found across multiple large populations. But the evidence is not without limitations.

What critics of UPF research argue

• Most of the evidence comes from observational studies, which cannot rule out confounding. People who eat more UPF may also exercise less, sleep less, smoke more, or have lower incomes, all of which independently affect health.
• The NOVA system has been criticised for grouping together very different products. A mass-produced wholegrain loaf and a packet of flavoured crisps are both NOVA 4, but their nutritional profiles are very different.
• Some researchers argue that the harm is primarily explained by the nutritional composition of UPF (high sugar, fat, salt, low fibre) rather than anything specific to the processing itself, and that a nutrient-based approach to regulation would be more precise.
• The UK's SACN and the 2025 US Dietary Guidelines Advisory Committee have both noted that while the associations are concerning, the certainty of evidence has limitations, and it is not yet possible to say definitively that processing itself, beyond its nutritional consequences, is independently harmful.

What proponents respond

• The Hall et al. RCT (2019) controlled for nutritional composition and still found UPF diets caused higher calorie intake and weight gain, suggesting processing has an independent effect beyond nutrients.
• Not a single study in the 2024 BMJ umbrella review found a beneficial association between UPF and any health outcome.
• The consistency of findings across very different populations, study designs, and countries is itself meaningful evidence.

The SACN position (2025)

The UK's Scientific Advisory Committee on Nutrition has described consistent associations between higher UPF consumption and adverse health outcomes as "concerning". Its existing dietary advice, to base the diet on fruit, vegetables, and whole grains, and to limit foods high in saturated fat, salt, and free sugars, is already broadly consistent with a low-UPF dietary pattern. SACN plans to review the evidence again in 2026.

Common UPF products in the UK, and what to look for

You do not need to read every label in detail. The quickest signal is the ingredient list. If it contains ingredients you would not find in a kitchen, or if it contains more than five or six ingredients, it is worth taking a closer look.

Practical steps to reduce UPF in your diet

The goal is not perfection. Shifting from a very high UPF diet to a moderate one is achievable and is likely to be meaningful for health. Here are practical steps grounded in what the evidence suggests.

1. Cook from whole ingredients when you can. Even simple meals made from fresh or frozen vegetables, whole grains, pulses, eggs, or plain meat sit in NOVA 1 to 3. Batch cooking and freezing portions removes much of the convenience argument for ready meals.
2. Read ingredient lists, not just nutrition labels. A product can have a reasonable-looking calorie count but still contain a long list of additives. If the ingredient list is very long, or contains words you do not recognise, it is likely NOVA 4.
3. Swap breakfast cereals for plain oats. Most branded breakfast cereals are ultra-processed. Plain porridge oats are NOVA 1. Adding fruit and plain nuts keeps it whole and nutritious.
4. Choose plain dairy. Plain whole milk yogurt and plain milk are NOVA 1. Most flavoured yogurts, flavoured milks, and yogurt drinks are NOVA 4.
5. Check your bread. Most supermarket sliced bread is ultra-processed. Look for a short ingredient list: flour, water, yeast, salt. Many sourdoughs and artisan loaves qualify.
6. Rethink snacks. Most packaged snacks, even those marketed as "healthy", are NOVA 4. Plain nuts, fruit, boiled eggs, and plain cheese are not.
7. Drink water. Fizzy drinks, flavoured waters, fruit squashes, diet drinks, and most shop-bought juices are ultra-processed. Water, plain sparkling water, plain tea, and plain coffee are not.
8. Use the Food Insight tool. Scan a product barcode to see its NOVA processing group alongside the full nutrition panel and any additives of concern.

Key statistics at a glance