What is an underrated party meal

Why the biscuit tempts us to overeat - the underestimated danger of highly processed foods

We get a large part of the energy we need every day from highly processed foods. These influence our eating behavior more than we would like - with sometimes drastic consequences.

Snacks, convenience food, ready meals, fast food - the list of well-sounding names is long, but it's always about the same thing: industrially manufactured foods that we can consume quickly, conveniently and at a reasonable price. Another thing in common: unlike an apple or a piece of meat, this meal consists of many ingredients and additives that make the product long-lasting, attractive to look at and tasty.

Processed food is with us every step of the way. The processing can go more or less far and serve different goals. Some processing steps are necessary for the production of olive oil, canned fish, bread, pasteurized milk, artisanal cheese or frozen vegetables. But that has little to do with what makes highly processed, so-called ultra-processed foods.

During their production, an important part of the original food - or raw material - is often eliminated. For example, refined flour is used in which the bran and the germs of the grain have been eliminated. The flour has a long shelf life and is very fine. During the refining process, however, a large part of the naturally present proteins, minerals, vitamins and trace elements are lost. From a nutritional point of view, whole grain products are therefore preferable.

Ultraprocessed foods are a growing concern of doctors and nutritionists. Because many of us already get more than half of the energy we need every day from such food. A clear definition is still lacking to distinguish processed products from ultra-processed products. The Nova classification introduced a good ten years ago can, however, provide an orientation here (see table).

Food: Classification according to the degree of processing

The higher the level, the less of it should be eaten.
processing Examples
Level 1: Fresh Foodfresh, dried, heated, pressed, fermentedVegetables, mushrooms, herbs / spices, fruit, nuts, seeds, cereals (flour), potatoes, meat, fish, eggs, milk, yogurt, quark, cheese, tea, coffee
Level 2: Ingredients, easily processedpressed, refined, ground, dried, crushedSalt, sugar, honey, vegetable oils, vinegar, corn starch, baking powder
Level 3: Processed foodssmoked, baked, cured, preserved, fermentedBread, pasta, jams, spreads, pickled vegetables, preserves of all kinds, preserves, beer, wine
Level 4: Heavily processed foods (ultra-processed)industrially produced, mostly with additivesReady-made products, cereals, bars, milk products with added fruit, baked goods and confectionery, sausage and fish products with additives

With this classification, the diplomat crème of a large Swiss bakery would also have to be regarded as a clearly ultra-processed product. The carbohydrates here come from modified potato starch, modified corn starch and sugar, among other things. There is also plenty of fat from whole cream and palm fat, proteins from eggs and wheat. The list of ingredients also includes a good dozen chemical stabilizers, thickeners, preservatives, colors and flavorings.

High energy density is a problem

Such additives are often given as E numbers. They are checked in Switzerland by the Federal Food Safety and Veterinary Office. If they are allowed, the food treated with them should not harm us directly. But how does ultra-processed food affect our health in the medium and long term? The facts look less optimistic here. For several years there has been increasing evidence that high consumption not only promotes obesity and type 2 diabetes. A large-scale study from France suggests that this also increases the risk of cardiovascular diseases and cancer.

“Probably the biggest problem with ultra-processed foods is that they tempt us to overeat,” says Wolfgang Langhans, professor emeritus for physiology at ETH Zurich. This is done through various mechanisms. For example, ultra-processed foods such as industrially manufactured apple pie, in contrast to less heavily processed apple juice or natural apples, usually have a high energy density.

This means that we can take in a lot of calories in a short period of time. If we do not consciously take breaks while eating such foods, there is a high risk that we will perceive the physiological feeling of satiety too late - at a time when we have already eaten beyond our hunger.

"This risk is much lower with little processed food," explains Langhans. Because these foods are usually richer in fiber and contain more water. "Both of these things go hand in hand with a larger volume of food, which is why the expansion of the stomach wall begins more quickly as an early signal of satiety."

Similar to drugs, alcohol or sex

The better a food tastes, the greater the risk that we will overeat. Because we don't just eat to survive, but also to enjoy food. We express this dualism in the motivation to eat with the words "hunger" and "lust". In order to increase the palatability of their products, the companies not only provide them with flavorings, but also with lots of sugar, fat and salt. This cocktail triggers feelings of happiness in our brain - via neurotransmitters such as dopamine or serotonin. This type of reward can encourage us to keep eating and later reach for the cookie that makes us feel this way.

“The reward reaction in the brain triggered by food is very similar to that with drugs, alcohol or sex,” says Langhans. More recent studies have also shown that the reward effect is greatest when a food - as is usual with ultra-processed products - not only contains a lot of fat or a lot of carbohydrates, but both. Such a combination is rather uncommon with natural foods, according to Langhans.

Because this (hedonistic) reward reaction in the brain is closely linked to the physiological regulation of hunger and satiety, the body can normally fine-tune the intake of calories and nutrients. This allows many people to maintain their weight despite the excess of food and not suffer from nutritional deficiencies. ‹As studies in recent years have shown, it is precisely this interaction between gastrointestinal and brain that could be disrupted by ultra-processed products. Artificial sweeteners are suspected, for example, which impart sweetness to the brain, but without delivering the calories expected by the body when this sensation occurs. Such a discrepancy could trigger signals in the direction of “eat more”, according to Langhans.

Clean experiment confirms hypothesis

The fact that ultra-processed foods can encourage us to overeat and thus make us fat has been discussed for years. It was not until 2019, however, that Kevin Hall's research group from Bethesda in the USA carried out a clean scientific experiment that is considered by experts to confirm this hypothesis. The doctors have called 20 healthy adults to their hospital for 28 days. There they were served ultra-processed or freshly prepared food for 14 days. In the following 14 days they got the other meal, so all subjects went through both diets.

In both regimes, they were served three large meals and snacks. They could eat as much of it as they wanted. The food in the two study groups differed only insignificantly in terms of the number of calories offered or the amount of carbohydrates, proteins, fat, sugar and salt. The big difference was in the source of the calories. In the first case, more than 80 percent of these came from ultra-processed foods, in the second case the same proportion came from under-processed foods.

The researchers were able to show that the same subjects in the phase with the ultra-processed diet averaged 500 kilocalories more a day and after two weeks they weighed just under one kilogram more. Even if this result is impressive, it does not answer all questions. After the short study period, it remains unclear what the results mean for the long-term development of weight. In addition, not all subjects gained weight in the study with the ultra-processed diet; in some, however, the weight gain was over 5 kilograms.

"The differences are likely to be primarily genetic," says the physiologist Langhans. This was shown impressively by a Canadian study published in 1990 on twelve identical pairs of twins. They had been overfed with 1000 kilocalories a day. After 14 days, the average weight gain was a good 8 kilograms - with the individual people having gained between 4 and 13 kilograms. As it turned out, the variation between the different pairs of twins was three times as great as within the pairs of twins.

Langhans is not surprised that the genome plays a central role in regulating weight. "The genes are the building instructions for proteins that perform important functions in the body as enzymes, receptors or peptide hormones," he says. Even small differences in activity could affect how well someone absorbs or burns food. As with engines, metabolic efficiency is not the same for all people. While some can get rid of a lot of energy by releasing heat, others would prefer to store the energy.

More fat kids and teenagers

"Not only obese people and people with a familial risk of being overweight should refrain from using ultra-processed foods," says internist and President of the Federal Nutrition Commission Philipp Schütz. Because when it comes to food, not only the quantity but also the quality have to be taken into account. "We know that even slim people benefit from a healthy diet with fresh and little processed food," emphasizes the chief physician at Aarau Cantonal Hospital.

In Switzerland, the topic is unfortunately hardly on the radar, says the doctor. But that will probably change in the next few years. The Federal Nutrition Commission wants to make ultra-processed foods one of its next priority topics. Because there are more and more of these products, says Schütz. "And we are seeing more and more children and young people in the hospitals, some of whom are extremely overweight."

But because of this, completely demonizing snacks and convenience food cannot be the goal, emphasizes the doctor. As always in medicine: "The dose makes the poison." The longer-term goal in educating people about healthy eating behavior must be to get away from counting calories and instead only eat with healthy hunger. With this approach, however, choosing the right food is key, says Schütz.

My food, my identity: Diet influences us more than many think. It can make you healthy, but it can also make you sick. For some it is hype, for others it is a substitute religion. Which Diet Really Help? How healthy is vegan food? And what tips do top athletes give? The NZZ is devoted to a series of the most important questions about food - from production to enjoyment to the effect on our lives.

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