Hall says the new study wasn't designed to see what exactly it is about ultra-processed foods that drives overeating, but the findings do suggest some mechanisms.
"One thing that was kind of intriguing was that some of the hormones that are involved in food intake regulation were quite different between the two diets as compared to baseline," Hall says.
For example, when the participants were eating the unprocessed diet, they had higher levels of an appetite-suppressing hormone called PYY, which is secreted by the gut, and lower levels of ghrelin, a hunger hormone, which might explain why they ate fewer calories. On the ultra-processed diet, these hormonal changes flipped, so participants had lower levels of the appetite-suppressing hormone and higher levels of the hunger hormone.
Another interesting finding: Both groups ate about the same amount of protein, but those on the ultra-processed diet ate a lot more carbs and fat. There is a concept, called the protein leverage hypothesis, that suggests that people will eat until they've met their protein needs. Hall says that this seems to be the case in this study and it partially explains the difference in calorie consumption they found. Even though the meals were matched for calories and nutrients, including protein, the ultra-processed meals were more calorie-dense per bite. In part, that's because ultra-processed foods tend to be low in fiber, so researchers had to add fiber to the beverages served as part of these meals to match the fiber content of the unprocessed diet. That means participants on the ultra-processed diet might have had to munch through more carbs and fat to hit their protein needs.
And one last finding of note: People ate much faster — both in terms of grams per minute and calories per minute — on the ultra-processed diet. Hall says it might be that, because the ultra-processed foods tended to be softer and easier to chew, people devoured them more quickly, so they didn't give their gastrointestinal tracts enough time to signal to their brains that they were full and ended up overeating.
www.npr.org
Could it be because all of our food is full of shite chemicals?
