A New Study Says To Stop Eating Ultra-Processed Foods If You’re Hoping To Lose Weight


Say out loud that you want to lose weight and you’ll pretty much immediately get flooded by a sea of self-styled experts tossing out anecdotal advice (even though experts say that short-term, restrictive diets of any kind simply don’t work in the long term).

“You gotta try intermittent fasting,” a colleague might say at dinner, after ordering two cheeseburgers at once. “I only eat one meal a day and I’ve never felt better.”

“My cousin lost 80 pounds doing Keto,” your waiter will chime in, as she plops a basket overflowing with buttery rolls on your table. “She cut out the bread and it practically fell off.”

“Have you heard of souping?” wonders a notorious cheese thief, dressed in all black, slowly descending on a string from the skylight above your table. “Lost five pounds on broth. Feel like a million bucks.”

And of course, there are always the “Fad Diets don’t work! It’s all about fewer calories!!!” people.

But while reducing calories does seem to be the most tried and true method for many to drop pounds (at least on a short-term basis), a new, first-of-its-kind study by the National Institutes of Health has found that calories may matter less than the kind of food you’re consuming. Researchers discovered that ultra-processed foods — bacon, frozen foods, junk food, packaged bread, and even yogurt with added fruit or sugar — caused more weight gain in participants than diets with minimally processed foods, like: eggs, nuts, whole veggies and fruit, and fresh meat, even when all other nutrition factors, including calories, were the same.

So is our reliance on the Trader Joe’s frozen food section the reason we don’t feel cute in a bathing suit? Maybe. The highly-controlled study was unique in that they had 20 subjects, 10 men and 10 women, living in a designated facility for four weeks. This allowed them to ensure all conditions were the same for all participants — including preventing participants from not reporting cheats. They then fed half of the subjects ultra-processed foods and the other half a minimally processed diet. After two weeksn, they switched groups. Meaning, all participants tried both diets for two full weeks. And all of the subjects were offered meals with the exact same calories, sugar, fat, fiber, carbs, and protein, though the participants could stop eating once they felt full.

The study found that over the two weeks of eating the more processed food, subjects gained an average of two pounds. While when eating foods in a more natural state, they actually lost two pounds. So, why did that happen? Well, one of the reasons, researchers say, is that those eating the ultra-processed foods tended to eat more of their meal.

“We found people over-ate on average more than 500 calories a day on the ultra-processed diet,” the study’s author Kevin Hall told NBC News. “They gained weight and gained body fat.”

When asked to rate both types of meals, subjects didn’t rate the more processed meal as any better tasting than its healthier alternative, but they still ate more if it. People also ate faster per minute when eating the ultra-processed food, researchers reported. They theorized this is possibly because it tended to be softer and easier to chew than the purer ingredients. Finally, when eating the less-processed diet, subjects had more of hormone, PYY, in their systems. This hormone can make you feel full. They also had less of a hormone that makes you hungry, ghrelin.

This was a small study and it remains to be seen if these results can be recreated or are a fluke. Still, they suggest that changing from more processed and packaged foods to more whole foods may be a long-term diet change that could help with sustained weight-loss. Obviously, eating fresher, less-processed food that you make yourself sounds like it would be better for you. Now science seems to be backing that up.

“This is the first study to show the nutrients on the nutrition facts labels aren’t the whole story,” Hall told NBC News. “There’s something else about those ultra-processed foods.”