Quick quiz. Which of these is ultra-processed: a loaf of bread, a pot of yoghurt, or a carton of oat milk?
The honest answer is: it depends which one you picked up. A bakery loaf made from flour, water, salt and yeast isn’t. A supermarket loaf with emulsifiers, preservatives and added sugar usually is. Plain yoghurt isn’t. A strawberry-flavoured, sweetened, thickened one generally is. That’s the first useful thing to know about ultra-processed food: it isn’t a type of food. It’s a way of making food. And once you can spot it, it becomes much easier to understand why some days your energy feels like a rollercoaster.
What “ultra-processed” actually means
Most researchers use a system called NOVA, which sorts food into four groups by how much it’s been processed:
1 · Whole / minimally processed
Fruit, veg, eggs, plain milk, oats, frozen peas, dried beans
2 · Kitchen ingredients
Oil, butter, salt, sugar, flour — used to cook with
3 · Processed
Cheese, tinned fish, simple bakery bread, salted nuts
4 · Ultra-processed
Soft drinks, packaged snacks, most breakfast cereals, instant noodles, many ready meals
The first three groups are what people have cooked with for generations. Group 4 is different. These are industrial products mostly made from refined ingredients — starches, sugars, oils, protein isolates — plus additives you wouldn’t find in a home kitchen: emulsifiers, flavourings, sweeteners, colourings. According to the Harvard T.H. Chan School of Public Health, they now make up a large share of the calories many people eat every day.
Worth saying clearly: “processed” isn’t the enemy. Frozen vegetables, tinned beans, plain yoghurt and wholegrain bread are processed, and they’re excellent. The problem is specifically the heavily reformulated stuff at the far end.
Why it messes with your energy
Many ultra-processed foods are low in fibre and protein and high in quickly-absorbed carbohydrates. So they hit your bloodstream fast. Your blood sugar rises, your body releases insulin to deal with it, and an hour or two later you often feel flatter than before you ate — tired, a bit foggy, and hungry again. Which, conveniently, makes the next quick snack look very appealing.
That’s the rollercoaster. A soft drink and a pastry at 11 a.m. is a classic way to set up the afternoon slump by 2 p.m.
There’s a second part to it. Many of these products are soft, easy to eat quickly, and carefully tuned to a combination of sugar, salt and fat that’s hard to stop eating. Because they’re low in fibre and bulk, the signals that normally tell you you’re full arrive late. You can eat a lot before your body notices — and then feel sluggish and heavy afterwards, which is the opposite of what you wanted from a meal.
The study that changed the conversation
For years, the obvious objection was: maybe ultra-processed food is just higher in sugar and fat, and that’s the whole story. In 2019, a team at the US National Institutes of Health tested that directly. Twenty adults lived in a research unit for four weeks. For two weeks they were offered ultra-processed meals; for two weeks, minimally processed ones. Both diets were matched for calories, sugar, fat, fibre and salt on offer, and people could eat as much as they wanted.
On the ultra-processed diet, they ate about 500 more calories a day — and gained weight. On the minimally processed diet, they ate less without trying and lost weight. The study was small, and researchers are still debating exactly why it happens — speed of eating, softness, energy density are all candidates. But it showed that the processing itself seems to matter, not just the nutrition label.
The 30-second label test
You don’t need to memorise NOVA. Turn the pack over and ask three questions:
1. Is the ingredient list long? Five or six recognisable ingredients is a good sign. Fifteen or twenty is usually not.
2. Are there things you wouldn’t have in your kitchen? Words like “modified starch,” “emulsifier,” “flavouring,” “glucose-fructose syrup,” “hydrolysed protein,” or sweeteners are the tell-tale marks of Group 4.
3. Is the front of the pack shouting? “High protein!” “Low fat!” “Added vitamins!” on a snack bar or cereal is often a clue that something heavily engineered is trying to look healthy.
Two out of three, and it’s very likely ultra-processed. That doesn’t mean “never.” It just means “not every day.”
Easy swaps that actually stick
The approach that works isn’t banning things. It’s crowding better options in, so the ultra-processed ones naturally take up less space. A few swaps that do a lot of the work:
| Instead of… | Try… |
|---|---|
| Sugary breakfast cereal | Porridge oats with fruit, or eggs on wholegrain toast |
| Fizzy drink or sweetened iced tea | Sparkling water with lemon, or plain tea |
| Crisps or a packaged snack bar | A handful of nuts, fruit with cheese, or plain yoghurt |
| Flavoured yoghurt | Plain yoghurt with berries and a little honey |
| Ready meal most weeknights | A simple batch-cooked meal, frozen in portions |
| Supermarket sliced white bread | Bakery or wholegrain bread with a short ingredient list |
A general trick: pair carbohydrates with some protein or fat. Cheese with crackers, nut butter on toast, yoghurt with fruit. It slows the sugar down and keeps your energy steadier. There are more ideas in our guides to snacks for steady energy and the best breakfast for energy. And if sugar is the main thing you reach for, cutting back on sugar goes into that specifically.
Please don’t turn this into a purity test
This is where a lot of advice goes wrong. Ultra-processed food isn’t poison, and trying to eliminate it completely usually ends the same way strict diets do — you manage for a while, then rebound. Ultra-processed products are also cheap and convenient, and for many people on a tight budget or with little time, they’re a realistic part of life.
What shapes your energy is the pattern, not the exceptions. If most of what you eat most days is whole or minimally processed food, the occasional packet of biscuits or takeaway pizza doesn’t undo anything. The British Heart Foundation takes the same practical line.
Our take: aim for “mostly real food, most of the time,” change one or two daily habits first — usually breakfast and drinks — and see how your afternoons feel after a couple of weeks. For the bigger picture of what to put on the plate, see eating for steady energy.
General information, not medical advice. If you’re dealing with persistent fatigue, or have a health condition that affects your diet or blood sugar, please speak with a healthcare professional or a registered dietitian.