Ultra-processed foods and your diet after 40

There is a version of eating healthily after 40 that involves a lot of effort: cooking everything from scratch, reading every label, avoiding anything in a packet. Most people cannot sustain that, and most of the time, they should not need to. Processing food is not inherently harmful. Freezing vegetables, canning beans, fermenting yoghurt, and baking bread are all forms of food processing, and they all make eating easier and more varied.

But there is a specific category of highly engineered food products, distinct from ordinary processed foods, where the research has become increasingly difficult to ignore. These are what nutrition researchers now classify as ultra-processed foods, and the evidence accumulated over the past decade about their effects on human health is substantial enough to warrant serious attention from anyone thinking carefully about what to eat after 40.

1. What are ultra-processed foods, exactly?

The most widely used framework for classifying ultra-processed foods is the NOVA system, developed by Monteiro and colleagues at the University of Sao Paulo. As described in their 2019 paper in Public Health Nutrition, NOVA classifies foods into four groups based on the extent and purpose of processing, not their nutrient content.[2]

• Group 1: Unprocessed or minimally processed foods. Fresh, frozen or dried fruits, vegetables, legumes, eggs, meat, fish and plain dairy. These are foods in their natural state or modified only by drying, freezing, pasteurising or fermenting.
• Group 2: Processed culinary ingredients. Oils, butter, sugar, salt and flour. These are extracted from natural foods and used as ingredients in cooking, but are not typically consumed on their own.
• Group 3: Processed foods. Foods made by combining Group 1 and Group 2 items: canned fish, cheese, cured meats, freshly baked bread, simple fruit preserves. These are processed but recognisable as foods.
• Group 4: Ultra-processed foods. Industrial formulations made mostly from substances extracted from foods, with little or no whole food content. They typically contain long lists of additives including emulsifiers, stabilisers, artificial flavours, colours and sweeteners not found in home kitchens.[2]

The distinction between Group 3 and Group 4 is not always immediately obvious, which is part of why ultra-processed foods are so pervasive. A loaf of bread made from flour, water, salt and yeast is a processed food. A commercial sliced loaf with 20-plus ingredients including preservatives, emulsifiers, dough conditioners and added sugars is ultra-processed. The category is defined by the industrial formulation process and the purpose of the additives, not simply by the number of ingredients.

Common ultra-processed foods

• Mass-produced packaged bread, rolls and bakery products
• Soft drinks, energy drinks, flavoured milk and fruit-flavoured drinks
• Packaged sweet snacks: biscuits, cakes, muesli bars, chocolate bars
• Packaged savoury snacks: crisps, crackers, flavoured popcorn, puffed snacks
• Breakfast cereals with added sugar, flavours or coatings
• Instant noodles, packaged soups, instant mashed potato
• Chicken nuggets, fish fingers, processed meat products including many deli meats
• Flavoured yoghurts and dairy desserts
• Most fast food items
• Meal replacement shakes and bars
• Margarine and other flavoured fat spreads

2. How much are we actually eating?

Ultra-processed foods now account for a substantial proportion of dietary energy across developed countries. Research by Machado and colleagues (2019) applying NOVA to Australian dietary data, published in Public Health Nutrition, found that ultra-processed foods contributed approximately 42% of total energy intake in Australian adults, with younger adults consuming higher proportions.[3] In the United Kingdom, Rauber and colleagues (2020) found the figure is closer to 57% of total energy intake, as reported in the European Journal of Nutrition.[4] In the United States, Hall and colleagues (2019) noted it exceeds 60% of daily energy for most adults.[5]

3. What the research shows about health outcomes

The 2024 BMJ umbrella review by Lane and colleagues is the most comprehensive synthesis of evidence to date. Across the 45 meta-analyses reviewed, covering nearly 10 million people, the consistent finding was that higher ultra-processed food consumption was associated with meaningfully worse health outcomes across almost every category examined.[1]

Key findings from that review included:

• A 50% increased risk of cardiovascular disease-related death associated with higher ultra-processed food intake
• A 48 to 53% higher risk of anxiety and common mental health disorders
• A 12% higher risk of type 2 diabetes per 10% increase in the proportion of the diet made up of ultra-processed foods
• A 21% higher risk of all-cause mortality
• Associations with higher rates of obesity, depression, sleep problems, and several cancers including colorectal and breast cancer[1]

It is important to be clear about what this evidence does and does not show. These are largely observational studies: they show association, not proven causation. People who eat more ultra-processed foods tend to differ from those who eat fewer in multiple ways, including income, education, physical activity and stress, and researchers can only partially control for these factors. However, the consistency of the findings across nearly 10 million people, different countries, and 32 different health outcomes is striking. And there are plausible biological mechanisms, described in the next section, that explain why ultra-processed foods might drive the harms the observational research suggests.[7]

4. Why ultra-processed foods are specifically problematic: the mechanisms

They are engineered to override satiety

One of the most important studies on this question is a randomised controlled trial by Hall and colleagues at the US National Institutes of Health, published in Cell Metabolism in 2019. Unlike the broader observational literature, this was a controlled feeding study, which addresses many confounding concerns.

Participants were randomly assigned to either an ultra-processed food diet or an unprocessed food diet for two weeks, then crossed over to the other. The diets were matched for total calories, sugar, fat, fibre and macronutrients offered. Participants could eat as much or as little as they wanted. People on the ultra-processed food diet consumed an average of 508 additional calories per day compared to when they were eating unprocessed food, and gained an average of 0.9kg. On the unprocessed diet, they spontaneously ate less and lost an average of 0.9kg.[5] The ultra-processed food did not satisfy hunger in the same way, even when matched on paper for key nutrients.

The researchers noted that people consumed ultra-processed foods significantly faster, suggesting they may have exceeded satiety signals before those signals had time to register. It may also relate to what was absent from the ultra-processed foods despite the nutrient matching: the complex mix of phytochemicals, intact fibre structures and micronutrients in whole foods that appear to contribute to satiety in ways nutritional science has not yet fully characterised.

Gut microbiome disruption

The human gut microbiome plays roles in digestion, immune function, inflammation, mood regulation and metabolic health. After 40, gut microbiome diversity tends to decline naturally, making it more important and more difficult to maintain a diverse microbial community.

Zinöcker and Lindseth (2018), writing in Nutrients, identified several mechanisms by which ultra-processed foods disrupt the microbiome: they are typically low in the prebiotic fibre that gut bacteria ferment for energy; many contain emulsifiers such as polysorbate 80 and carboxymethylcellulose, which animal model research suggests may disrupt the gut's protective mucus layer and alter microbiome composition; and several artificial sweeteners used in ultra-processed foods have been shown in human studies to alter gut bacteria populations in ways that worsen glucose tolerance.[8]

Chronic inflammation

Ultra-processed foods drive chronic low-grade inflammation through multiple pathways. Furman and colleagues (2019), in a comprehensive review published in Nature Medicine, described how dietary patterns high in refined sugars, omega-6-heavy seed oils and food additives contribute to systemic inflammation by disrupting gut barrier integrity, promoting pro-inflammatory immune cell activation, and reducing the anti-inflammatory short-chain fatty acids produced by healthy gut bacteria.[9]

After 40, baseline inflammatory markers tend to rise gradually in a process sometimes called inflammageing. A diet high in ultra-processed foods accelerates this process and is a plausible contributor to the increased risk of inflammatory conditions seen in the BMJ umbrella review data.[1]

Nutrient displacement

Perhaps the most straightforward mechanism is the simplest one: when ultra-processed foods make up a large proportion of the diet, they displace the foods the body needs most. Monteiro and colleagues (2013), in Obesity Reviews, found that higher ultra-processed food consumption was consistently associated with lower dietary protein, fibre, vitamins and minerals at the population level.[10] For people over 40, where adequate protein and fibre intake are already particular challenges, this displacement effect compounds the biological changes of midlife.

5. Why this matters more after 40

The mechanisms described above affect people at all ages. But several factors make ultra-processed food consumption particularly consequential in midlife and beyond.

As Wilcox (2005) in Clinical Biochemistry Reviews established, insulin sensitivity declines progressively with age, making blood sugar spikes from ultra-processed, high-glycaemic foods more damaging and longer-lasting.[11] Gut microbiome diversity naturally decreases from midlife onward, as documented by Claesson and colleagues (2012) in Nature, so the additional disruption from emulsifiers and low-fibre ultra-processed diets comes on top of an already declining baseline.[12] The inflammatory tendency of midlife, documented by Furman and colleagues (2019) in Nature Medicine, is worsened by the chronic inflammation driven by ultra-processed food consumption.[9] And the body's requirement for protein and micronutrients is, if anything, higher after 40 than before, making nutrient displacement more costly.

There is also the cumulative nature of these effects to consider. The harms reflected in the BMJ umbrella review data represent the endpoint of long-term dietary patterns. Someone in their 40s who has been eating a diet high in ultra-processed foods since their 20s is not starting from zero, and the time to change those patterns is before the clinical consequences have fully manifested.

6. A practical approach: reducing ultra-processed foods without making eating miserable

The goal is not food purity. It is a practical shift in the proportion of the diet that comes from whole and minimally processed foods versus industrial formulations. Research by Srour and colleagues (2019) in The BMJ found a 12% increase in cardiovascular disease risk per 10% increment in the proportion of ultra-processed foods in the diet, suggesting that even moderate reductions in UPF intake carry meaningful health benefit at the population level.[13]

Start with the highest-volume sources

The most effective place to start is with the ultra-processed foods that make up the largest volume of your current intake, not necessarily the ones you enjoy most. For most people this includes:

• Packaged breakfast cereals. Swap for rolled oats or whole grain options with minimal ingredients. Reynolds and colleagues (2019) in The Lancet found that higher whole grain intake was among the dietary factors most strongly associated with reduced risk of type 2 diabetes and cardiovascular disease.[14]
• Packaged bread. Look for bread with five ingredients or fewer: flour, water, yeast, salt, sometimes a seed or grain. Or switch to genuine sourdough, which uses traditional fermentation rather than industrial additives and produces a lower glycaemic response than commercial equivalents.
• Flavoured yoghurt. Replace with plain Greek yoghurt. The difference in protein content, sugar content and additive load is substantial, and as discussed in our weight loss after 40 article, protein adequacy is a cornerstone of body composition after 40.
• Packaged snacks. Replacing them with nuts, whole fruit, boiled eggs, or cheese addresses the convenience need without the industrial additive load.

Cook more, but not necessarily more elaborately

The single most effective practical shift away from ultra-processed foods is cooking from recognisable ingredients. This does not require elaborate meals. A piece of grilled fish with frozen vegetables and boiled rice is not complicated. A tin of legumes heated with garlic, tomatoes and spices takes ten minutes. The barrier is usually habit and kitchen confidence rather than time or skill.

Useful shortcuts that do not compromise the goal: frozen vegetables (nutritionally comparable to fresh, per a review by Li and colleagues in Journal of Food Composition and Analysis, 2017), canned legumes, canned fish in water or olive oil, plain full-fat dairy, eggs, and whole grains in bulk. These are the infrastructure of a minimally processed diet that is genuinely practical to maintain.[15]

Read ingredients, not just nutrients

The nutrition information panel tells you macronutrients and some micronutrients. The ingredient list tells you what the food actually is. As Monteiro and colleagues (2019) advised in Public Health Nutrition, the presence of substances not normally used in home cooking, including emulsifiers, stabilisers, artificial flavours, colours and sweeteners, is the practical indicator that a product is ultra-processed, regardless of what the nutrient panel says.[2]

Putting it all together: a realistic framework

Here is a practical approach that the evidence supports, without requiring a complete overhaul of how you eat:

• Aim for 80% of your diet to come from Group 1 and Group 3 foods (whole, minimally processed, and simply processed foods). The remaining 20% can include ultra-processed items without undermining your overall dietary pattern. This approach is consistent with the dose-response relationships identified by Lane and colleagues (2024) and Srour and colleagues (2019).[1][13]
• Replace your highest-volume ultra-processed foods first, not necessarily your favourites. Changing breakfast and snacks typically has more impact than agonising over one biscuit with afternoon tea.
• Build meals around protein and vegetables. This naturally reduces the proportion of ultra-processed food in your diet, because most ultra-processed foods are not protein and vegetable sources.
• Use convenient minimally processed foods strategically. Canned fish, frozen vegetables, plain yoghurt, tinned legumes and whole grain staples make a whole-food diet practical rather than aspirational.
• Read ingredient lists, not just nutrition panels, when making choices about packaged foods. Look for the industrial additives that mark a product as ultra-processed per the NOVA criteria.[2]