Ultra-Processed Foods: What Are They, and Should We Avoid Them?
Updated: Oct 13
Written by Rosy Allan, BSc (Hons), ANutr
Registered Associate Nutritionist | Level 3 Personal Trainer | Level 4 Cancer Exercise Rehabilitation Specialist
Ultra-processed foods have become one of the most widely debated topics in nutrition. From breakfast cereals and packaged bread to ready meals and protein bars, we're increasingly encouraged to question how our food is made.
But is food processing itself harmful? Are all ultra-processed foods nutritionally poor? And does improving your diet mean giving up convenient foods altogether?
The science is more nuanced than many headlines suggest.
Understanding what food processing means, and what the research actually shows, can help us make informed dietary choices without creating unnecessary fear around food.
What are ultra-processed foods?
Food processing refers to the methods used to prepare, preserve or alter foods before we eat them.
This can include anything from freezing vegetables and pasteurising milk to producing packaged snacks and ready meals.
Researchers commonly use the NOVA classification system, developed at the University of São Paulo, to categorise foods according to the extent and purpose of their processing.
The system divides foods into four groups.
Group 1: Unprocessed or minimally processed foods
These are foods that remain close to their original form or have undergone relatively simple processes such as washing, freezing, drying or pasteurisation.
Examples include:
Fresh and frozen fruit and vegetables
Oats, rice and other grains
Eggs and plain milk
Beans and lentils without added flavourings
Plain yoghurt
Unsalted nuts and seeds
These foods can provide important nutrients, including fibre, protein, vitamins and minerals.
Group 2: Processed culinary ingredients
These are substances obtained from foods or nature and used primarily in cooking or seasoning.
Examples include:
Olive oil and other vegetable oils
Butter
Sugar
Salt
They're generally used alongside other foods to prepare meals rather than eaten alone.
Group 3: Processed foods
These are typically made by adding ingredients such as salt, sugar or oil to foods from Group 1.
Examples include:
Tinned fish in oil
Some cheeses
Vegetables preserved in brine
Traditionally made bread with a small number of ingredients
Processing can improve food safety, preservation and convenience. A processed food isn't automatically an unhealthy food.
Group 4: Ultra-processed foods
Ultra-processed foods are generally industrial formulations made using ingredients or processes that are not commonly used in domestic cooking.
They may contain substances such as emulsifiers, flavourings, modified starches or other ingredients designed to alter texture, taste, appearance or shelf life.
Examples can include:
Sugary soft drinks
Many packaged cakes and biscuits
Some breakfast cereals
Instant noodles
Certain ready meals
Some commercial breads and flavoured yoghurts
However, the NOVA category alone doesn't tell us everything about a food's nutritional quality.
A high-fibre wholegrain bread may be classified as ultra-processed, while butter and sugar fall into different processing categories. That doesn't mean butter and sugar are automatically healthier choices.
What does the research say about ultra-processed foods and health?
A substantial body of research has examined associations between ultra-processed food consumption and health outcomes.
A 2024 umbrella review published in The BMJ examined 45 pooled analyses involving nearly 9.9 million participants.
Higher consumption of ultra-processed foods was associated with increased risk across several health outcomes, including type 2 diabetes, cardiovascular disease and mortality (Lane et al., 2024).
These findings are concerning, but there is an important distinction between association and causation.
Much of the research is observational. Although researchers attempt to account for other factors, it can be difficult to establish whether the associations arise from food processing itself, nutritional composition, overall dietary patterns or related lifestyle factors.
The UK's Scientific Advisory Committee on Nutrition highlighted these uncertainties in its 2025 evidence update.
It remains unclear how much of the observed risk is attributable specifically to processing rather than factors such as high salt, saturated fat, free sugars, energy density or low fibre intake (SACN, 2025).
This doesn't mean the findings should be ignored. It means we should interpret them carefully.
What happens when researchers compare different diets?
Randomised controlled trials can help investigate the effects of different dietary patterns under more controlled conditions.
In a small 2019 trial, 20 adults consumed an ultra-processed diet and an unprocessed diet for two weeks each.
When eating the ultra-processed diet, participants consumed approximately 500 additional calories per day and gained weight. During the unprocessed diet, their energy intake was lower and they lost weight (Hall et al., 2019).
Although compelling, the trial was short and involved only 20 participants. It cannot establish the long-term effects of every type of ultra-processed food.
More recently, a UK randomised crossover trial published in Nature Medicine compared minimally processed and ultra-processed diets that both followed the principles of the Eatwell Guide.
Over eight weeks, participants experienced an average weight reduction of approximately:
2.06% on the minimally processed diet
1.05% on the ultra-processed diet
Both diets produced weight loss, but the minimally processed diet resulted in a greater reduction (Dicken et al., 2025).
The study offers useful evidence that the level of processing may influence dietary intake and weight outcomes, even when both diets are designed around healthy eating guidance.
However, it was relatively small and short-term. Its results should not be interpreted as proof that all ultra-processed foods cause weight gain.
Are all ultra-processed foods unhealthy?
No. This is where blanket advice to avoid every ultra-processed food becomes problematic.
Some products classified as ultra-processed can contribute useful nutrients to a balanced diet.
For example, certain fortified breakfast cereals provide fibre and added micronutrients. Some packaged wholegrain breads are practical sources of fibre, while convenient plant-based products may make it easier for people to meet their dietary needs.
Conversely, a food can be minimally processed and still be consumed in amounts that don't support a person's nutritional goals.
The nutritional value of a food depends on several factors, including its overall composition, portion size, frequency of consumption and contribution to the wider diet.
Rather than judging a food solely by its processing category, I encourage looking at the bigger picture.
Why can ultra-processed foods be so easy to overconsume?
One factor worth considering is how convenience influences our eating habits.
Think about preparing a spaghetti bolognese from scratch. You need to buy the ingredients, bring them home, prepare the vegetables, cook the meal and clean up afterwards. Compare this with purchasing a ready-to-eat meal that can be eaten within minutes.
Modern food production has dramatically reduced the time and effort required to access food. While this convenience can be valuable, particularly for people managing demanding schedules, it may also make frequent eating easier.
The physical characteristics of some ultra-processed foods may also influence consumption. Softer textures, higher energy density and faster eating rates can make it easier to consume substantial amounts of energy before feeling satisfied.
In the controlled trial by Hall et al. (2019), participants consumed approximately 500 additional calories per day when eating an ultra-processed diet and ate at a faster rate. However, the study could not determine precisely which food characteristics caused the increased intake.
Importantly, convenience itself is not unhealthy. A nutritious ready meal, frozen vegetables or microwave rice can make a balanced diet more achievable.
The goal isn't to make food preparation unnecessarily difficult. It's to understand how convenience, food composition and our wider eating environment can influence dietary choices.
How can you make healthier choices without avoiding everything?
The aim doesn't need to be eliminating every packaged or processed food from your diet.
Instead, consider a few practical approaches.
1. Prioritise nutritional quality
Choose foods that contribute valuable nutrients to your diet.
Look for opportunities to include more vegetables, fruit, wholegrains, beans, lentils, nuts and other fibre-rich foods.
2. Use food labels constructively
The length of an ingredient list isn't a reliable measure of how healthy a food is.
Instead, consider the nutritional information, particularly fibre, saturated fat, salt and free sugars, alongside the food's wider role in your diet.
3. Make convenient foods work for you
Frozen vegetables, tinned beans, microwave rice and some ready-prepared foods can make eating well easier. Convenience is not something to feel guilty about. For someone working long shifts, managing a family or coping with fatigue, practical food options may be essential to maintaining a balanced diet.
4. Consider your overall dietary pattern
An occasional biscuit or ready meal doesn't determine your health. What matters more is the pattern of eating you maintain over time. Regularly choosing nutrient-rich foods while allowing flexibility is generally more realistic than following restrictive food rules.
Final thoughts
Research increasingly links diets high in ultra-processed foods with poorer health outcomes, and controlled trials suggest that food processing and food formulation may influence energy intake and weight.
However, the evidence doesn't justify treating every ultra-processed food as equally harmful.
The NOVA system is a useful way of understanding food processing, but it shouldn't replace consideration of nutritional quality, dietary balance and individual circumstances.
As a nutrition professional, I believe dietary advice should help people make informed choices rather than create anxiety around everyday foods.
A healthy diet doesn't need to be perfect. It needs to be nutritious, practical and sustainable.
At ROSY, we offer personalised online nutrition consultations and coaching throughout the UK, helping you make evidence-based dietary changes that work for your lifestyle.
Disclaimer: This article is provided for general nutrition education and should not replace individualised advice from an appropriately qualified healthcare professional. Dietary recommendations may need to be adapted for specific medical conditions and nutritional requirements.
References
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, pp. 3297–3308. Available at: https://doi.org/10.1038/s41591-025-03842-0
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), pp. 67–77.e3. Available at: https://doi.org/10.1016/j.cmet.2019.05.008
Lane, M.M. et al. (2024) 'Ultra-processed food exposure and adverse health outcomes: Umbrella review of epidemiological meta-analyses', BMJ, 384, e077310. Available at: https://doi.org/10.1136/bmj-2023-077310
Scientific Advisory Committee on Nutrition (SACN) (2025) Processed foods and health: SACN's rapid evidence update. London: Office for Health Improvement and Disparities. Available at: https://www.gov.uk/government/publications/processed-foods-and-health-sacns-rapid-evidence-update
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