New research published in The American Journal of Clinical Nutrition has shown that consuming only unprocessed foods may cut over 300 calories per day while not decreasing the size of meals.
The research included a post-hoc analysis of a randomized controlled trial on the effects of eating ultra-processed and unprocessed foods. The trial included twenty adults who were given free access to either an ultra-processed diet or an unprocessed diet for two weeks, followed immediately by the alternate diet for an additional two weeks. The meals provided to the participants were matched in calories, energy density, macronutrients, sugar, salt, and fiber. The participants were told to eat as much or as little as they wanted with no restrictions. The amounts and types of foods each participant consumed were tracked along with their weight during both phases of the study. The initial study showed that consuming an ultra-processed diet tended to lead to greater calorie consumption and weight gain, and this post-hoc analysis sought to clarify the nutritional characteristics of the meals that participants selected during the unprocessed and ultra-processed phases of the study.
The results showed that when the participants were consuming the unprocessed diet, they tended to choose more foods with low energy density (mostly fruits and vegetables). This choice meant that most of the unprocessed meals had fewer calories overall while containing larger mass compared to the ultra-processed meals. A nutritional analysis of these meals showed that the fruits and vegetables added to the unprocessed diets added many essential vitamins and minerals that would have been missing otherwise.
The authors of the study noted that the unprocessed diets may have eventually led to micronutrient deficiencies if the participants had not consistently chosen to eat low-calorie fruits and vegetables with their meals. The authors theorized that people prioritize micronutrient-rich foods at the expense of high-calorie foods when given the option. This may partially explain why people gain weight on an ultra-processed diet, since most ultra-processed foods are both high in calories and rich in micronutrients. This result suggests that prioritizing unprocessed foods may moderate calorie intake, which could have benefits for many aspects of health, including the heart and the metabolic system.
Sources: The American Journal of Clinical Nutrition, Science Daily