Ultra processed food and the way it quietly rewires appetite and metabolism
Most people think of ultra processed food as “a few treats here and there”.
In reality, for many adults it now makes up most of what they eat in a day.
Across large population studies, higher ultra processed food intake is consistently linked with greater risk of obesity, type 2 diabetes, cardiovascular disease, metabolic syndrome, depression and earlier death.
But the more interesting question is how these foods change your appetite, metabolism and long term risk.
This is the lens we use in clinic at The Wellness.
What do we actually mean by ultra processed food
There is no single global definition, but most research uses the NOVA system. NOVA classifies foods into four groups from minimally processed (group 1) to ultra processed (group 4).
Ultra processed foods are typically
Industrial formulations made mostly from refined ingredients
Often containing additives you would not use at home (emulsifiers, flavour enhancers, modified starches, artificial sweeteners)
Designed to be hyperpalatable, convenient and long shelf life
Common examples include
Sugary drinks and many “energy” drinks
Packaged snacks and crisps
Many breakfast cereals and cereal bars
Instant noodles and some ready meals
Reconstituted meat products and some plant based “junk food”
Not every food that comes in a packet is ultra processed. Canned beans, frozen vegetables and plain yoghurt are technically processed but can still be nutritious. The problem is the overall pattern when ultra processed foods crowd out whole or minimally processed foods over time.
How ultra processed foods reshape appetite
One of the most important studies in this space came from the US National Institutes of Health. In a tightly controlled trial, adults lived in a research unit for four weeks and were given either an ultra processed diet or a minimally processed diet for two weeks each. The meals were matched for calories, macronutrients, sugar, fibre and sodium.
The only real difference was the degree of processing.
What happened
On the ultra processed diet, people ate around 500 extra calories per day without trying to
They gained weight over two weeks
On the minimally processed diet, they spontaneously ate fewer calories and lost weight
Why this matters
People were not told to “eat as much as you like” on one diet and “restrict” on the other. They had access to food in the same way. But the ultra processed meals were softer, easier to eat quickly and more energy dense. This combination meant more calories before the brain had time to register fullness.
From what we see in clinic, this shows up in everyday life as
Meals that disappear quickly without much chewing or awareness
Less satisfaction after eating, leading to more snacking
A gradual upward drift in calorie intake over months and years
The end result is not just weight gain, but a nervous system and appetite system that starts to expect this pattern of eating.
Blood sugar volatility and insulin resistance
Ultra processed foods are often high in refined starches and sugars, low in fibre and protein, and very easy to digest. This means blood sugar tends to rise quickly and then fall just as quickly.
Over time this pattern is associated with
Higher fasting glucose and insulin
Higher risk of insulin resistance and type 2 diabetes
Greater likelihood of developing metabolic syndrome clusters of high blood pressure, central obesity, abnormal lipids and raised blood sugar
Clinically, people describe this as
Energy crashes mid morning or mid afternoon
Intense cravings for something sweet or starchy
Feeling “hangry” if meals are delayed
When we switch people towards higher fibre, higher protein, minimally processed foods, those swings usually flatten. Hunger becomes more predictable and easier to manage.
Overfed yet undernourished
Another problem with ultra processed diets is nutrient dilution.
When a high proportion of your daily intake comes from ultra processed foods, you can hit or exceed your calorie needs but still fall short on
Fibre
Vitamins and minerals (for example magnesium, potassium, folate)
Phytochemicals and other protective compounds in plants
Large observational studies and umbrella reviews have found that greater exposure to ultra processed foods is linked with higher risk of cardiometabolic disease, some cancers and earlier mortality, even after adjusting for calories and basic nutrients.
In other words, it is not just “too many calories”. The pattern of ingredients and the absence of protective nutrients also matters.
You do not need perfection for meaningful change
In many high income countries, ultra processed foods now account for more than half of total energy intake for adults. For some groups, it is closer to 60 or 70 per cent.
The good news is that you do not need to go from 70 per cent to zero.
Research in people with metabolic risk shows that reducing ultra processed food intake and replacing it with minimally processed, nutrient dense options can improve blood pressure, lipids, waist circumference and insulin sensitivity over time.
In our clinic, we often see early shifts in
Fasting glucose and insulin
Triglycerides and HDL
Markers of liver fat
Subjective energy and cravings
within a few weeks of changing the pattern of foods, without strict dieting.
A simple seven day experiment
Rather than trying to overhaul your entire diet at once, treat this as a short experiment.
Step one
Notice your current baseline
For two or three days
Write down everything you eat and drink
Put a star next to anything that is clearly ultra processed
You do not need an app or calorie tracking. The goal is awareness.
Step two
Choose one swap per day
For the next seven days, pick one ultra processed item each day and swap it for a more whole food alternative. For example
Sugary cereal → oats with berries and yoghurt
Crisps at 3pm → handful of nuts and a piece of fruit
Fizzy drink → sparkling water with a squeeze of citrus
Frozen ready meal → pre cooked grains, frozen veg and rotisserie chicken or tinned beans
Step three
Make the better choice the easier choice
Keep whole food options visible and ready to eat
Move ultra processed snacks off the desk or out of the main kitchen sightline
If evenings are your weak point, prepare or buy something simple but satisfying in advance
At the end of seven days, check in with
Energy through the day
Cravings between meals
How full you feel after eating
If this experiment helped, extend it for another week and add one more swap.
What is the first ultra processed snack or meal you would swap if you started this tomorrow?
Frequently asked questions
Are all processed foods automatically bad for you
No. “Processed” covers a huge range from frozen berries and wholemeal bread to confectionery and instant noodles. Ultra processed foods are a subset defined by their industrial formulations, additives and the way they behave in the body and at population level. Canned beans, frozen vegetables and plain yoghurt can absolutely be part of a healthy pattern.
Is it ever okay to eat ultra processed foods
For most people, yes. The issue is not the occasional ice cream or packet of crisps. The concern is when ultra processed foods form the backbone of the diet breakfast, snacks, lunch, dinner, and drinks. The evidence linking ultra processed intake to adverse outcomes is based on overall exposure, not isolated moments.
What if I rely on convenience because of time or cost
Some convenience options are still relatively minimally processed
Frozen vegetables and fruit
Tinned fish, beans and lentils
Pre cooked whole grains
Ready prepared salads with simple ingredients
If you choose convenience foods that are still built around recognisable ingredients and short, simple ingredient lists, you move your diet in a better direction without adding much time.
How we approach this at The Wellness
At The Wellness we look beyond generic advice and use blood work, body composition and sometimes continuous glucose monitoring to see how your current pattern of eating is affecting your metabolism.
From there we help you
Identify the ultra processed foods that are doing the most damage
Design swaps and meals that fit your lifestyle, not an idealised version of it
Track objective markers so you can see changes, not just guess
You do not have to eat perfectly. But nudging your diet away from ultra processed foods and towards real, recognisable ingredients is one of the most reliable ways to support appetite, metabolism and long term health.
If you tried the seven day experiment, what would be the very first swap you would make?