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Trending Science: Eating processed foods makes people eat more and put on weight

Landmark study finds processed food causes overeating and weight gain.


No one needs to be told ultra-processed foods that are significantly changed from their original state and filled with sugar, fat, additives, preservatives and artificial colours harm our health. So why are the findings in the journal ‘Cell Metabolism’ surprising to the medical community? The research shows that sugar, salt and fat didn’t seem to be what was urging people to overeat. “I was surprised by the results,” Dr Kevin Hall, lead author and senior investigator at the National Institutes of Health’s National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) in the United States told ‘Time’. “It’s the first trial that can actually demonstrate that there is a causal relationship between something about ultra-processed foods—independent of those nutrients—that cause people to overeat and gain weight.” Craving more food, eating faster Over a month-long period, 20 healthy adults split equally among males and females ate ultra-processed and unprocessed meals. Both groups received three meals a day, drinks and snacks. After the first 2-week period, they switched. The results reveal that the volunteers who ate a diet of ultra-processed foods consumed more calories and put on more weight and body fat compared to those who ate a diet of unprocessed foods. Both diets had the same amounts of calories, sugars, fibre, fat and carbohydrates. Participants ate as much or as little as they wanted. People on the ultra-processed diet ate about 500 calories more a day than they did on the unprocessed one. They also ate faster and gained weight, but lost weight on the unprocessed diet. They gained about 1 kg during the 2 weeks on the ultra-processed diet, and lost about the same amount on the unprocessed diet. “Ultra-processed food tends to be softer, which makes it easier to chew and swallow,” Dr Hall said. “One of the theories is that if you’re eating more quickly, you’re not giving your gut enough time to signal to your brain that you’ve had enough calories and that you’re full and to stop eating. By the time the brain gets that signal, it’s too late—you’ve already overeaten.” “Research like this is an important part of understanding the role of nutrition in health and may also help people identify foods that are both nutritious and accessible — helping people stay healthy for the long term,” noted NIDDK Director Dr Griffin P. Rodgers in a National Institutes of Health news release. Low price and convenience come at a cost In the study, the ingredients for the unprocessed meals cost about 40 % more than for the ultra-processed foods. Because healthier food options are more expensive, many consumers find it difficult to avoid ultra-processed food. However, cutting down is well worth the extra price and effort. “We have to be mindful that it takes more time and more money to prepare less-processed foods,” Dr Hall concluded in the news release. “Just telling people to eat healthier may not be effective for some people without improved access to healthy foods.”


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