Food · 5 min read ·

Ultra-processed foods: why we eat more of them

Crisps, sugary cereals, frankfurters, instant soups. What makes them “ultra” — and why do we eat more of them than we want?

In a nutshell

1Four levels of processing

Researchers at the University of São Paulo sorted food into four groups by processing, the NOVA system: unprocessed and minimally processed foods (vegetables, fruit, meat, milk, eggs), culinary ingredients (oil, butter, sugar, salt), processed foods (such as cheese or fresh bread) and ultra-processed products.1

Definition 1 ingredient is enough A product is ultra-processed when its ingredient list contains at least one substance never used in home cooking — such as high-fructose corn syrup, hydrogenated fats or hydrolysed proteins — or additives meant to make food tastier or more appealing: flavourings, flavour enhancers, colours, emulsifiers, sweeteners.1

2The experiments that changed the debate

Moderate evidence +508 kcal a day 20 adults spent a month at the clinical centre of the US National Institutes of Health (NIH). For two weeks they ate an ultra-processed diet, for two weeks an unprocessed one — with the same calories, sugar, fat, salt and fibre on the plate. They could eat as much as they liked. On the ultra-processed diet they ate 508 kcal more a day and gained 0.9 kg; on the unprocessed diet they lost 0.9 kg.2
Moderate evidence 2× more weight lost In England, 55 people with overweight or obesity twice ate, for 8 weeks each, a diet that followed official healthy-eating guidelines — once made of minimally processed foods, once of ultra-processed ones. They lost weight on both, but about twice as much on the minimally processed diet: 2.1% of body weight versus 1.0%.3

3What large studies show

Moderate evidence 9.9 million people A 2024 review of 45 pooled analyses: more ultra-processed food was linked to 32 of the health outcomes studied. The most convincing links were with death from cardiovascular disease (50% higher risk), type 2 diabetes, anxiety and common mental disorders. These are observational studies — association does not mean causation.4
Moderate evidence +4% mortality A US study followed more than 114,000 nurses and health professionals for over 30 years. Those who ate the most ultra-processed food died 4% more often than those who ate the least. The strongest link was with ready-to-eat meat products such as processed meats; other groups varied.5

Related articles: Salt, Meat.

What to take from this

Sources

Written on , based on studies available at that date. Newer research may change the conclusions.

  1. Monteiro C. A. et al. (2019). Ultra-processed foods: what they are and how to identify them. Public Health Nutrition 22(5):936–941. doi.org/10.1017/S1368980018003762
  2. Hall K. D. et al. (2019). 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.e3. doi.org/10.1016/j.cmet.2019.05.008
  3. Dicken S. J. et al. (2025). Ultraprocessed or minimally processed diets following healthy dietary guidelines on weight and cardiometabolic health: a randomized, crossover trial. Nature Medicine 31:3297–3308. doi.org/10.1038/s41591-025-03842-0
  4. Lane M. M. et al. (2024). Ultra-processed food exposure and adverse health outcomes: umbrella review of epidemiological meta-analyses. BMJ 384:e077310. doi.org/10.1136/bmj-2023-077310
  5. Fang Z. et al. (2024). Association of ultra-processed food consumption with all cause and cause specific mortality: population based cohort study. BMJ 385:e078476. doi.org/10.1136/bmj-2023-078476

This is general information and does not replace a doctor or dietitian. Processing is just one property of food — how much you eat and what it is made of matter too.