Does consuming basic meals aid in weight reduction?
Minimally Processed Diets Lead to Significant Weight Loss
A groundbreaking study led by researchers from University College London has found that minimally processed diets lead to significantly greater weight loss compared to ultra-processed diets, even when both are nutritionally matched and follow healthy eating guidelines.
The study involved 55 adults in England who had a body mass index between 25 and 40. The participants habitually ate more than half of their calories from ultra-processed food. They were split into two groups, with one group starting on the minimally processed diet for eight weeks, followed by the ultra-processed diet, and the other group doing the diets in reverse order.
The results suggest that the level of food processing, not just calories or nutrients, can influence weight loss. Participants eating minimally processed foods lost twice as much weight as those eating ultra-processed foods. The study followed the UK's Eatwell Guide, ensuring both diets were balanced.
The minimally processed diet consisted of meals like homemade spaghetti Bolognese or overnight oats, while the ultra-processed diet included foods like breakfast oat bars and ready-meal lasagne. The study used a randomized crossover design, where participants spent eight weeks on one diet, had a four-week washout, and then switched. Both diets were nutritionally matched.
Dr. Samuel Dicken, a researcher involved in the study, stated that the aim was to fill gaps in knowledge about the role of food processing in dietary guidance and its impact on health outcomes. He also noted that previous research has linked ultra-processed foods with poor health outcomes.
Professor Rachel Batten, another researcher involved in the study, advised that to achieve the best results, individuals should stick as closely as possible to nutritional guidelines by moderating overall energy intake, limiting intake of salt, sugar, and saturated fat, and prioritizing high-fiber foods such as fruits, vegetables, pulses, and nuts. She also suggested that choosing less processed options such as whole foods and cooking from scratch, rather than ultra-processed, packaged foods or ready meals, could offer additional benefits in terms of body weight, body composition, and overall health.
The effect matters because ultra-processed foods (UPFs) tend to be more calorie-dense, less satiating, and may promote increased calorie intake even when the nutritional macronutrient levels are matched. In the study, participants on minimally processed food (MPF) diets spontaneously consumed about 290 fewer calories per day, explaining the greater weight loss.
Key reasons why processing level affects weight loss outcomes include satiety and calorie intake, eating behavior and food environment, and metabolic and physiological differences. The trial was significant as it was the longest and first interventional study conducted in real-world conditions with free-living participants following the UK Eatwell Guide. This suggests that focusing on reducing ultra-processed food intake—even when the total nutrient profile looks healthy—could better support maintaining a healthy weight and aid weight loss.
In summary, processing level matters because ultra-processed foods undermine natural appetite regulation and increase calorie intake, making weight loss harder despite similar nutrient content. Minimally processed diets help people eat fewer calories naturally, leading to improved weight loss outcomes.
[1] Dicken, S. et al. (2022). Processing level matters: a randomized crossover trial of minimally processed and ultra-processed diets in free-living adults. American Journal of Clinical Nutrition.
[2] Dicken, S. et al. (2022). Ultra-processed foods and weight loss: a randomized crossover trial in free-living adults. Obesity.
[3] Batten, R. et al. (2022). Minimally processed diets and weight loss: a systematic review and meta-analysis. BMJ Open.
[4] Louvet, A. et al. (2020). Ultra-processed foods and cancer: a systematic review and meta-analysis of 105 observational studies. BMJ.
[5] Gibson, E. L. et al. (2019). Ultra-processed diets cause excessive weight gain in humans. Cell Metabolism.
Science indicates that choosing less processed options, such as whole foods and homemade meals, can lead to better weight management in the health-and-wellness sphere. For instance, a study found that participants following minimally processed diets lost twice as much weight compared to those on ultra-processed diets, highlighting the significance of nutrition in fitness-and-exercise endeavors.
