New research indicates that adhering to a wholefood diet allows individuals to consume significantly more food while reducing their overall calorie intake. A study led by scientists at the University of Bristol found that participants who followed an unprocessed food diet consumed over 50% more food than those who opted for ultra-processed foods (UPFs), yet averaged 330 fewer calories daily. The findings, published in The American Journal of Clinical Nutrition, provide valuable insights into dietary choices and suggest that humans possess an inherent ability to select nutritious foods when presented in their natural state.
The research was conducted by a team including Professor Jeff Brunstrom, who serves as the lead author. The study examined dietary patterns and revealed that individuals consuming only wholefoods prioritized fruits and vegetables, sometimes eating several hundreds of grams per meal, instead of higher-calorie options such as rice, meat, and butter. This led to participants on the unprocessed diet consuming approximately 57% greater volumes of food by weight compared to those consuming UPFs.
This investigation reanalyzed data from a landmark clinical trial led by Dr. Kevin Hall of the National Institutes of Health, which initially demonstrated that UPFs contribute to excessive calorie intake and weight gain. The Bristol team uncovered intriguing mechanisms that explain why those eating wholefoods could enjoy larger quantities while maintaining a lower calorie count. The study highlighted that the nutritional profile of the diet, rich in essential vitamins and minerals from fruits and vegetables, would not have been achieved through a diet consisting solely of calorie-dense foods.
Co-author Mark Schatzker, a noted author in nutrition, emphasized that had participants consumed only high-calorie foods, they would have experienced deficiencies in essential nutrients. Instead, the inclusion of lower-calorie fruits and vegetables filled these micronutrient gaps. The researchers propose a concept termed “micronutrient deleveraging,” suggesting that humans instinctively choose nutrient-rich foods over energy-dense options when given the choice.
The findings also raised concerns about the effects of UPFs, which contrary to the belief that they provide “empty calories,” may still meet micronutrient needs, often through fortification. For instance, calorie-rich foods such as French toast sticks and pancakes were found to deliver significant vitamin A, while the majority of vitamin A from the wholefood diet came from carrots and spinach, which are much lower in calories.
Dr. Annika Flynn, a senior research associate at the University of Bristol, noted that UPFs might present a risk of calorie overload by combining high energy content with micronutrients, undermining the beneficial balance seen in wholefoods. She stated, “This raises the alarming possibility that UPFs deliver both high energy and micronutrients in one hit, which could result in calorie overload.”
This research provides further understanding of how dietary choices are influenced by food composition, especially as highly processed foods become increasingly prevalent in society. Professor Brunstrom remarked, “Overeating is not necessarily the core problem. Our research demonstrated that consumers on a wholefood diet actually ate far more than those on a processed food one, but the nutritional makeup of food influences choices.”
The study is supported by the National Institute for Health and Care Research (NIHR) and the Bristol Biomedical Research Centre, which aims to translate scientific discoveries into improved health outcomes. With findings suggesting that presenting healthier options can lead to better dietary choices, this research may pave the way for strategies to encourage wholefood consumption, thereby promoting better nutrition and weight management.
For further information or interviews with the lead researchers, contact Victoria Tagg, News & Content Manager at the University of Bristol, via email at [email protected]. The study will be available online upon the lifting of the embargo on March 15, 2024.
