Ultra-processed food: what the category means and whether it is useful

The term ultra-processed food comes from the NOVA classification, developed by Carlos Monteiro's group in Brazil. It sorts foods not by nutrient content but by the extent and purpose of industrial processing.

Group 1 is unprocessed or minimally processed — fruit, vegetables, meat, milk, eggs, grains. Group 2 is culinary ingredients — oil, butter, salt, sugar. Group 3 is processed foods, made by combining groups 1 and 2 — bread, cheese, tinned fish, cured meat. Group 4, ultra-processed, describes industrial formulations typically containing ingredients not used in home cooking: emulsifiers, thickeners, colours, flavourings, sweeteners, protein isolates.

In several high-income countries, ultra-processed food supplies more than half of total energy intake — around 57 per cent in the United States and roughly 55 per cent in the United Kingdom.

The evidence, and its shape

Large cohort studies from France, Spain, the United States and elsewhere consistently associate higher ultra-processed food intake with cardiovascular disease, type 2 diabetes, obesity, some cancers and all-cause mortality. The associations survive adjustment for nutrient intake, which is the interesting part — it suggests something beyond the sugar, salt and fat content.

The obvious objection is confounding. People eating more ultra-processed food differ systematically in income, education, smoking, activity and much else. Statistical adjustment cannot fully handle that.

Which is why the one randomised trial in this area matters disproportionately.

The Hall trial

Kevin Hall's group at the US National Institutes of Health ran a controlled feeding study in which twenty adults lived in a metabolic ward and ate either an ultra-processed or an unprocessed diet for two weeks each, in random order. The diets were matched for calories presented, sugar, fat, fibre and macronutrients. Participants could eat as much or as little as they wanted.

On the ultra-processed diet they ate around 500 kcal more per day and gained weight; on the unprocessed diet they lost it.

The trial was small and short, and it is the only one of its kind. But it demonstrates something the cohort studies cannot: matched for nutrients, ultra-processed food led people to eat more. That points at the food itself rather than at the eater.

The problem with the category

NOVA is a blunt instrument, and its critics have a point.

Wholemeal supermarket bread is ultra-processed under NOVA because it contains emulsifiers. So is a supermarket baked bean. So is unsweetened fortified soy milk, most plant-based meat alternatives, many high-fibre breakfast cereals, and most protein supplements used in hospitals for malnourished older patients.

Meanwhile home-made cake with butter, sugar and white flour is not ultra-processed, nor is bacon or a deep-fried potato cooked at home.

This produces genuine absurdities and makes the category difficult to use in dietary guidance. Several countries have adopted it anyway; others, including the UK's advisory committee, have concluded the evidence is not yet strong enough to base recommendations on and that the mechanism remains unclear.

Why it matters particularly in later life

Two reasons pull in opposite directions.

Convenience food consumption rises with age, driven by reduced mobility, difficulty shopping, cooking for one, low appetite, and limited income. Ready meals, biscuits and soft foods requiring little chewing are exactly what an older person with poor dentition and low energy gravitates toward.

But an older adult who is undernourished has a different problem from a middle-aged adult who is overeating. Energy-dense, palatable, easily chewed food that requires no preparation may be exactly what a person losing weight needs. Fortified supplements are ultra-processed and they prevent real harm.

Advice that works for a 45-year-old can be actively harmful at 85, and this is one of the clearer examples.

A workable position

Rather than trying to eliminate a category defined by industrial technique, the more useful framing is what a diet is built around.

Cook from recognisable ingredients where you can. Eat vegetables, legumes, fruit, nuts, eggs, fish and dairy in quantity. Treat the reformulated snack aisle — the crisps, biscuits, confectionery, sugary drinks and pastries — as the genuine problem area, because that is where most of the ultra-processed energy in real diets actually comes from.

Do not agonise over wholemeal bread, tinned beans, frozen vegetables, plain yoghurt or fortified milk. And if you or someone you care for is losing weight and struggling to eat, ignore this entire subject and concentrate on getting enough in.