With the invention of tinned goods and pasteurization in the 19th century, food alchemy became possible on an industrial scale. Processing innovations made food cheaper, more convenient, and plentiful. According to the United Nations, the average daily food supply available to one person in the rich world increased by more than 20% between 1961 and 2021, to 3,500 kilocalories. In that time, obesity rates have more than tripled; Today, almost one in three people globally is obese or overweight.
There are now growing concerns that the heavy processing used to whip up cheap, tasty nibbles could be just as harmful. A particular target is “Ultra-Processed Foods” (UPFS), a relatively recent label put forward by Carlos Monteiro, a Brazilian scientist. Robert F. Kennedy Jr., Donald Trump’s nominee for Secretary of Health, has compared processed food to “poison.” And promised to reduce the share of stock in the American diet. Colombia introduced a tax on highly processed foods and drinks in November 2023. Authorities in Brazil, Canada and Peru have advised the public to limit consumption of these foods. MPs in Britain are investigating the effects of UPF on people’s health.
At the heart of the debate is a question: Are UPFS unhealthy because their nutritional content is poor, or does the processing somehow pose a risk in itself? New research may soon provide answers to what people eat.
At the turn of the 21st century, Dr. Monteiro observed that people in Brazil were buying less sugar and oil than in the past. Yet rates of obesity and metabolic diseases were still rising. This coincided with the increasing popularity of packaged snacks and ready meals, which were loaded with sugar, fat, and other additives.
In 2009 Dr. Monteiro came up with a classification system, called NOVA, which sorts foods into four buckets based on the degree of processing they undergo. The first group includes minimally processed foods, including fruits and milk. The second covers basic ingredients like butter and sugar. Next are foods like tinned vegetables, bread and cold cuts.
The fourth group, UPFS, includes heavily processed items, for example fizzy drinks, sugary cereals and frozen pizzas. These are ingredients not commonly found in home kitchens, such as hydrogenated oils, high-fructose corn syrup, flavoring agents, and emulsifiers. UPF is made by breaking down whole foods into components such as sugars, proteins, starches and fiber. These are chemically modified and reused along with additives such as artificial colors and sweeteners to make the food more appealing.
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The share of UPF in diets has increased worldwide since the 1990s; They now account for more than half of calorie intake in the US and UK (see chart). And over the decades, evidence has been building that these foods are harmful in some way. Several studies show that people who consume diets high in UPFS have more health problems, including obesity, type-2 diabetes, heart disease, various cancers, and mental-health problems. UPFs often contain higher concentrations of fat, sugar, and salt than processed foods, which may explain their negative effects. But a recent analysis by Samuel Dicken and Rachel Batterham at University College London reviewed 37 studies and found that even after adjusting for fat, sugar and salt UPFS were still strongly associated with poor health. This suggests that there is more to their harm than just a poor nutrient profile.
Where those losses come from is still unclear. With so many competing factors that can also explain poor health – such as income, education and social circumstances – studies alone cannot provide conclusive answers. Arne Astrup, a researcher at the Novo Nordisk Foundation in Denmark, argues that most studies that make statistical adjustments to try to isolate the effects of processing “are not sufficient”.
A better way to assess the question is with a randomized controlled trial (RCT), where researchers track a person’s food intake and control for all other variables. In one of the few such trials published in 2019, Kevin Hall, a researcher at the National Institutes of Health (NIH) in the US, admitted 20 adults to the NIH Clinical Center for four weeks. Participants received ultra-processed or minimally processed foods for two weeks before swapping diets for the next fortnight. Participants in both diets had access to the same amount of calories and nutrients, such as sugars, fiber and fat. People were free to eat as much as they wanted.
The results were striking. People on the ultra-processed diet ate about 500 more calories per day than those on the unprocessed diet. They ate fast and gained an average of 1 kilogram (2.2 lb) in two weeks. On other diets, participants lost the same amount of weight. Dr. Hall says that, although the study was small and conducted in an artificial setting, the results suggest that excess amounts of salt, sugar and fat are not entirely to blame for the ill effects of processed food. .
Dr. Further RCTs will be needed to confirm Hall’s results. Still, a big question remains – why do people overdo UPF? Dr. Hall has some ideas. One is that highly processed foods pack more calories per bite. When making them, manufacturers often remove water to dry the food, to improve their shelf life. But it also makes foods more energy dense.
Another theory – as anyone who has tried, and failed, to eat just one crisp from a bag, is that highly processed foods are also engineered to be irresistible. UPFS often contain combinations of nutrients—either fat and sugar or fat and salt, or high in carbohydrates and salt—known as “hyper-palatable” mixes. These combinations do not appear in nature and encourage people to eat more quickly, not enough, not enough, not enough, not enough time to tell the brain to eat more. Is full.
To test these ideas, Dr. Hall is running another study where 36 people check in on their diet for a month. They will be rotated through four different diets: the two in their previous study and two new ultra-processed regimes. One of these is low in both energy density and hyper-palatable foods, while the other is high in energy density but low in hyper-palatable combinations. As before, all diets are balanced for key nutrients and Dr Hall is tracking changes in participants’ weight and other health measures. Although full results of the study are not expected until next year, early findings suggest that both co-pilability and energy density seem to cause additional calorie consumption in the puffs. for Science. The extent of food improvement, meanwhile, is uncertain. If harms are focused on only a few ingredients or processing methods, foods can be easily adapted. However, Dr. If it turns out to be a “combinatorial nightmare” of multiple ingredients or processes that cause harm only in certain combinations, solving UPF problems will become much more challenging, Hall says. Properly mapping areas, however, this is. First step.
Even if the results show conclusively that processing, and not just for nutrients, leads to poor health, policy makers will face another difficulty: the definition of UPFS remains woolly. The Nova assortment has no tolerance for artificial ingredients. The mere presence of a chemical additive classifies a food as UPF, regardless of the amount. This may confound health results. For example, a recent observational study from Harvard University found that while some UPFs, such as sugary drinks and processed meats, were associated with a higher risk of heart disease, others, such as breakfast cereals, breads and yogurt, were associated with a higher risk of heart disease. Instead, they were connected to the lower ones. Risk for heart disease. Dr. Astrup warns that the current classification risks “watering down” a lot of healthy foods. Dr. Insights from Hall’s work may therefore help refine understanding of UPF, leading to more balanced and useful guidelines.
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