You probably already had a feeling you should skip the vending machine for an afternoon snack. But it turns out ultra-processed foods are even worse than we already thought. A new study, out in Cell Metabolism, shows these foods cause weight gain even when they don’t have more fat, sugar, or carbohydrates than their healthier counterparts.
There’s something about the processing itself that causes people to eat more before they feel full. On the flip side, switching to a whole food diet — even with no calorie restriction — can lead to measurable weight loss in just two weeks, the researchers found.
Claims like this crop up all the time, but it's always been tricky to isolate the "processed-ness" of various foods from other factors that often go along with it. The foods have more salt, sugar and fat; less protein, less fiber; and the people who eat them most might also have lower socioeconomic status, higher stress or exercise less.
But researchers wanted to get all that other stuff out of the way to look at whether processing foods alone made any difference. It was no small feat. “These kinds of studies are very rare and the way that we did this really relies on our ability to have the facilities that we do,” says Kevin Hall, lead researcher on the study. He’s chief of the Integrative Physiology Section at the National Institute of Health (NIH).
