A new study reveals that consuming an entirely unprocessed diet can help people eat more food while still consuming fewer calories. The research, conducted by scientists at the University of Bristol, highlights how individuals who embraced a wholefood diet ate over 50% more food than those following diets based on ultra-processed foods (UPFs) yet still managed to consume an average of 330 fewer calories each day.
Whole foods—foods as close to their natural state as possible—such as fruits, vegetables, grains, and lean proteins, were central to the study. The results offer fresh insights into how food choices can influence both health and caloric intake, offering a healthier alternative to heavily processed foods that may contribute to weight gain.
Wholefoods Encourage Smarter Choices
The study’s lead author, Professor Jeff Brunstrom, an experimental psychology professor at the University of Bristol, emphasized that when offered unprocessed options, people instinctively select foods that provide a balance of nutrition and fullness. “Our dietary choices are not random—we are making smarter decisions than previously assumed when foods are presented in their natural state,” Brunstrom explained. “It’s exciting to see that people’s intuitive food choices result in reduced energy intake while still feeling satisfied.”
Building on research from a 2019 study that demonstrated how UPFs led to excessive calorie intake, the team reanalyzed data to better understand how unprocessed diets led participants to select more fruits and vegetables, as opposed to higher-calorie wholefoods like rice, meat, and butter. Scientists believe this behavior stems from an innate “nutritional intelligence” prompting people to seek out micronutrient-rich foods.
Dr. Annika Flynn, senior research associate and co-author of the study, warned that UPFs could disrupt the balance between calories and nutrients. “This raises the possibility that UPFs combine both high energy and micronutrients, leading to calorie overload. Unlike wholefoods, which promote a competition between calories and nutrients, processed foods can undermine this healthy balance,” she said.
While the study confirmed that people on wholefood diets tended to eat larger quantities, it stressed that the nutritional makeup of food plays a significant role in shaping food choices. Professor Brunstrom concluded, “Overeating isn’t the problem. The issue lies in how UPFs nudge people towards higher-calorie options, which—even in smaller quantities—contribute to excess energy intake and potential obesity.”
