People who stick to a whole-food diet may be able to eat more food and still lose more weight, according to new research.
The study, published in The American Journal of Clinical Nutrition in December, found that participants eating a fully unprocessed diet consumed 57% more food by weight than those eating ultra-processed foods — yet took in about 330 fewer calories per day on average.
The difference lies in how ultra-processed foods can interfere with the body’s natural response to whole foods, researchers said.
The study was led by scientists at the University of Bristol in England and co-authored by U.S. nutrition experts from the National Institute of Diabetes and Digestive and Kidney Diseases in Maryland and McGill University in Canada.
It reanalyzed data from a landmark clinical trial led by longtime National Institutes of Health researcher Kevin Hall that found eating ultra-processed foods led to roughly 500 additional calories a day and weight gain.
The research revealed that when people ate unprocessed foods, they naturally gravitated toward large portions of fruits and vegetables — while leaving more calorie-dense foods like pasta, steak and cream unfinished.
The findings suggest that people may have an innate ability to balance nutrition and fullness, but only when food isn’t heavily processed, according to lead author Jeff Brunstrom.
“It’s exciting to see that when people are offered unprocessed options, they intuitively select foods that balance enjoyment, nutrition and a sense of fullness, while still reducing overall energy intake,” Brunstrom said in a statement.
“We seem to make much smarter decisions than previously assumed, when foods are presented in their natural state.”
Outside experts say the results line up with what clinicians see in practice.
“This adds to the understanding of the picture and to the metabolic challenges we face in the U.S. population,” said Frank Dumont, executive medical director at Virta Health in Colorado.
“One of the biggest changes here has been the increasing exposure to and the reliance on ultra-processed foods, where the final food product bears little resemblance to the underlying ingredients,” Dumont, who was not involved in the study, told Fox News Digital.
“If we have evolutionarily developed the ability to gauge the nutritional content and value of food … then disguising the foods via processing to a point where we cannot easily pick up on the cues regarding the actual ingredients has the potential to sabotage our ability to do this well.”
Registered dietitian Theresa Link, also with Virta Health, said it’s not surprising people can eat larger portions of whole foods without weight gain.
“Whole foods — like vegetables and fruits, healthy fats, plain meats and fish, eggs, full-fat dairy, nuts and seeds, beans and legumes, and high-fiber grains like steel-cut oats and quinoa — are naturally rich in fiber and/or protein,” Link said. “They provide more volume, require more chewing and help you feel full, which reduces the urge to overeat.”
Highly processed foods, she added, are different.
“They’re engineered to be hyper-palatable, with the perfect mix of salt, fat, carbs, sugar and texture that your brain loves. This combination triggers dopamine — the brain’s reward chemical — making it hard to stop eating.”
Experts caution, however, that the study involved just 20 participants and was conducted in a tightly controlled metabolic ward over only four weeks.
“The real world is certainly more challenging,” Dumont said. “For those of us not living in a metabolic ward, where all meals are prepared and provided, we have to navigate a complex food environment, and we have to make hundreds of nutritional decisions per day.”
Doctors agree that, while larger studies are needed, the findings offer practical guidance.
“Once patients wean themselves off a diet high in high-calorie, ultra-processed foods and instead focus on nutritious whole foods, weight management becomes much easier,” said Jennifer Brown, a West Virginia-based board-certified obesity medicine physician at MyObesityTeam, who also wasn’t involved in the research.
“Confirmation of these findings would support the idea that whole foods are much healthier and help with weight maintenance compared to ultra-processed foods,” she said.
Fox News Digital reached out to the study’s authors for comment.
