Research conducted by scientists at the University of Bristol reveals that adhering to a wholefood diet allows individuals to consume significantly more food while still lowering their overall caloric intake. Published in The American Journal of Clinical Nutrition in March 2024, the study indicates that those following an unprocessed food regimen ate over 50% more food by weight compared to individuals consuming ultra-processed foods (UPFs), yet they averaged 330 fewer calories daily.
The study, co-authored by prominent US nutritional experts, highlights a natural inclination towards healthier food choices when individuals opt for unprocessed options. Lead author Jeff Brunstrom, a Professor of Experimental Psychology at the University of Bristol, emphasized the significance of these findings. “When offered unprocessed options, people instinctively select foods that provide enjoyment, nutrition, and a sense of fullness, all while reducing their overall energy intake,” he stated.
Insights into Dietary Choices
The research revisited data from a critical clinical trial led by Dr. Kevin Hall from the National Institutes of Health. This earlier study demonstrated the link between UPF consumption and excessive calorie intake, but the new analysis sheds light on why individuals consuming solely wholefoods tend to eat larger volumes of food while maintaining a lower caloric load. Participants on the unprocessed diet frequently opted for fruits and vegetables, often consuming several hundred grams per meal, as opposed to more caloric options like meat and pasta.
The results indicated that participants on the unprocessed diet consumed 57% more food by weight, which was primarily made up of nutrient-rich fruits and vegetables. The research team further examined the nutritional quality of the participants’ diets. They found that the variety and volume of fruits and vegetables provided essential vitamins and minerals that would have been lacking had the participants chosen higher-calorie foods.
Co-author Mark Schatzker, an acclaimed author and food writer, noted, “Had participants consumed only calorie-rich foods, they would have fallen short on essential vitamins and minerals, leading to potential deficiencies. Lower-calorie fruits and vegetables filled these nutritional gaps.”
Understanding Nutritional Intelligence
The scientists propose a concept they term “micronutrient deleveraging,” suggesting that humans prioritize micronutrient-rich foods—such as fruits and vegetables—over energy-dense options. In contrast, the findings reveal that UPFs, which are often criticized for offering “empty calories,” may actually meet micronutrient requirements, sometimes through added vitamins. For instance, calorie-dense foods like French toast sticks and pancakes provided significant amounts of vitamin A. Conversely, in the unprocessed diet, vitamin A was primarily sourced from lower-calorie options like carrots and spinach.
Dr. Annika Flynn, a Senior Research Associate at the University of Bristol, expressed concern over the implications of these findings. “This raises the alarming possibility that UPFs can deliver both high energy and micronutrients simultaneously, potentially resulting in calorie overload,” she cautioned. “This undermines the beneficial balance that wholefoods promote, encouraging consumers to favour nutrient-dense choices over high-energy options.”
The study contributes valuable insights into the impact of highly processed foods on human behaviour and dietary decision-making. Brunstrom further clarified, “Overeating is not the core issue. Our research clearly demonstrates that individuals on a wholefood diet consume more than those on a processed food diet. However, the nutritional composition of foods influences choices, nudging consumers towards higher-calorie options that can lead to excess energy intake and obesity.”
Recent research from the same university supports these findings, noting that simply rearranging a menu to highlight healthier, environmentally-friendly dishes can encourage diners to make better choices. This concept of “healthy competition” seems to motivate individuals to select options that are both nutritionally beneficial and lower in calories.
The findings of this research have important implications for public health, particularly as the prevalence of ultra-processed foods continues to rise. As society grapples with rising obesity rates, understanding the interplay between food choices and nutritional quality is crucial in promoting healthier eating habits.
