New Food Study Confirms Worst Suspicions About Ultra-Processed Foods

A trial run by the US government could confirm the worst fears of anyone whose diet starts and ends up in the frozen food aisle. This suggests that people who consume mostly processed foods consume more calories and gain more weight than those who consume mainly unprocessed foods, even though both diets start with the same amounts of fat, carbohydrates and other foods. 39 other nutrients.

There is plenty of indirect evidence (and common sense) to suggest that diets rich in ultra-processed foods can be unhealthy and likely to cause weight gain. But according to the lead author of the study, Kevin Hall, a senior researcher at the National Institute of Diabetes and Digestive and Kidney Diseases, there is not much concrete evidence of a cause-and-effect relationship. This is a longstanding problem in the world of nutrition because it is difficult (and expensive) to study people's diets in isolation.

"There is this old saying that correlation is not necessarily synonymous with causality. For example, people who consume ultra-processed foods may be unhealthy in some other way. They could also be less rich than those who do not eat as rich in ultra-processed foods. So you do not know if ultra-processed foods could be an innocent bystander in all of this, "Hall told Gizmodo over the phone.

To address this deficiency, Hall and his team recruited 20 healthy volunteers who went on vacation for a month to the National Institutes of Health's Metabolic Clinical Research Unit for a randomized controlled trial – apparently the first of its kind never realized. But while their room and board were free, there was a major stipulation. For two weeks, they should feed on ultra-processed foods, while the other two weeks would be spent on unprocessed food. Half were randomly assigned to start the unprocessed diet first, and vice versa.

There is a debate about what exactly is an ultra-processed food. But Hall and his team have decided to follow the guidelines developed by the United Nations, which take into account the different types of industrial processing of a food or an ingredient before it ends up on our plate. Examples of ultra-processed breakfasts, highlighted by the authors, include pancakes, sausages and hash browns, while a mostly unprocessed breakfast includes blueberries, raw nuts and oat flakes.

"[Ultra-processed foods] it's hard to define, but you'll know it when you see it, "said Hall.

Dietitians have created meals for each diet and have designed them to approximate the total number of calories, macronutrients such as fat and sugar, sodium and fiber. Most importantly, the volunteers were invited to eat as much or as little as they wanted. In addition to the free snacks available, each person had the opportunity to consume up to twice as many calories a day as it would probably be necessary to stay at his current weight, based on an exam prior.

The final results of the team were striking. On the ultra-processed diet, volunteers consumed an average of 500 extra calories a day, taking body fat and about one pound of weight two weeks later; on the unprocessed diet, they lost body fat and fell from the same pound.

The results were published Thursday in cellular metabolism.

Although the findings may seem obvious on the surface, Hall explained that the reasons why people eat too much with an ultra-processed diet are unclear. In recent years, many experts have adopted the simple and intuitive idea that, since ultra-processed foods tend to be higher in fat, sugar and salt, it is these three nutrients that are largely to blame for weight gain, obesity, and metabolic disorders. But given the design of this study, this explanation seems to be lacking.

"I suspected somehow that once you would have found these nutrients – for fat, sugar, and salt – there would not be much difference, but I was wrong," he said. Lobby.

The study was not intended to go beyond the specific role of fats, sugar and salt in increasing our caloric intake. And the small sample size of the study means that the results should be viewed with some caution, at least until further research confirms them. But Hall said that there were some interesting clues as to why ultra-processed foods could make us gorging ourselves.

"When people were eating an unprocessed diet, the levels of a hormone called PYY, an appetite suppressant hormone secreted by the intestine, actually increased. And likewise, another hormone known to induce hunger, called ghrelin, died under an untransformed diet, "said Hall.

At this point, however, the specific ingredients or chemicals commonly found in ultra-processed foods that could be causing this hormonal shift towards increased consumption are unclear.

Another potentially important difference that they have noticed is that people eat ultra-processed foods much faster than unprocessed foods. This speed would probably have given their bodies less time to display the stop sign and give them the feeling of being satiated. The ease of eating ultra-processed foods may also have helped, as they were, on average, easier to chew and easier to chew than unprocessed foods.

Taste, on the other hand, was one of the most commonly cited factors for why ultra-processed foods can lead to weight gain that did not play any important role: volunteers said they enjoyed eat one diet than the other.

"It throws a wrench in this explanation too," said Hall. "But that's good news in a way. This suggests that if you are able to go from a diet containing ultra-processed foods to a diet without these foods, that does not necessarily mean that you will not like it less. "

Of course, if our stubborn human nature can make any lifestyle change a challenge, there are many reasons why it is objectively more difficult for many people to adopt a healthier diet. For example, many people living in the poorest neighborhoods can not easily reach fruit and vegetable shops, but are surrounded by fast food restaurants and vending machines.

But for those who are able to radically change their eating habits, Hall said their findings have a positive side – a solution that could even fix some barriers between supporters of different modes.

"There is a lot of debate in the scientific community, as well as in the public, about whether low carb or fat diets are the best way to lose weight or not. But one thing on which all these people from different sides of the food war tend to agree, is that we should eat less ultra-processed foods, "he said. Hall said. "It's intriguing to think that some of the successes attributed to a low-carbohydrate or fat diet could actually be due to changes in reducing the amount of ultra-processed foods in their diet – these This is at least an intriguing aspect. hypothesis to continue studying. "