The debate around Ultra-Processed Foods (UPFs) has often been polarised: are they harmful because of their nutrient content, their industrial processing, or both? For the first time, researchers have directly tested this question in a long-term randomised controlled trial (RCT) published in Nature Medicine. The UPDATE trial offers fresh insight into how UPF and minimally processed food (MPF) diets compare when both are aligned with healthy dietary guidance.
The Trial
The UPDATE trial is the first clinical study to directly compare UPF and MPF diets head-to-head—and the longest trial of UPF consumption to date.
Fifty-five UK adults took part in a 2 × 2 crossover RCT. Each participant was assigned two eight-week diets in random order: one UPF-based, the other MPF-based.
- The MPF diet included foods such as overnight oats and homemade spaghetti Bolognese.
- The UPF diet included foods such as packaged oat bars and ready-made lasagne.
Crucially, both diets followed the UK NHS Eatwell Guide, meeting recommendations for fat, saturated fat, carbohydrate, sugar, salt, fibre, and fruit and vegetable intake. Participants were provided with around 4,000 kcal of food per day, delivered to their homes, and told to eat as much or as little as they wished.
Between the two diets, participants underwent a four-week “washout” period on their normal eating pattern. In total, 50 participants completed at least one arm of the trial.
The Results
The trial’s primary outcome was body weight. Both diets led to weight loss—but the MPF diet produced nearly double the effect:
- MPF diet: –2.06% body weight
- UPF diet: –1.05% body weight
While this difference may sound modest, it is significant given the short eight-week duration and the fact that participants were not asked to restrict intake. When modelled over a year, the MPF diet would translate to around 9–13% body weight reduction, compared with 4–5% on the UPF diet.
Secondary outcomes added further detail:
- Body composition: The greater weight loss on the MPF diet was explained by larger reductions in fat mass and total body water, with no difference in fat-free mass.
- Craving control: Participants reported significantly improved craving control on the MPF diet.
- Cardiometabolic markers: Blood pressure, heart rate, and biomarkers either improved or remained stable on both diets.
The Conclusion
The UPDATE trial shows that processing level matters—even when diets are matched for nutrients according to national guidelines. Minimally processed foods supported greater weight loss, healthier body composition, and improved appetite regulation compared with ultra-processed foods.
At the same time, both diets delivered health benefits compared with baseline, reinforcing the importance of established dietary principles:
- Limiting salt, added sugar, and saturated fat
- Prioritising high-fibre foods like wholegrains, fruits, vegetables, legumes, and nuts
The trial highlights that MPF diets may make it easier to lose and maintain weight long term, but it also underlines that existing healthy eating guidance remains a powerful tool for improving health.
Policy Implications
The authors note that tackling obesity cannot rely solely on individual responsibility. Policy actions are needed to reshape food environments so that healthier, minimally processed options are accessible, affordable, and convenient. This could include reformulating products, redesigning food systems, and reconsidering the balance between UPFs and MPFs in public health messaging.
Nutricomms Opinion
The UPDATE trial marks an important moment in UPF research. For the first time, we see high-quality clinical evidence showing that processing level itself can influence weight outcomes—even when nutrient guidelines are equalised.
This raises important points for nutrition science and communication:
- Food structure matters: The satiety and sensory properties of MPFs may help explain their advantage for weight management.
- Nutrition still matters: Both diets, when aligned with guidance, led to health improvements. It is not a question of processing versus nutrition, but how the two interact.
- Communication must stay nuanced: Oversimplified “UPFs are bad” messages risk confusing consumers and overlooking beneficial or necessary processed foods.
For food businesses, this is a critical signal: reformulation must not only target nutrient profiles, but also consider food structure, satiety, and eating experience. For policymakers, the challenge is ensuring that minimally processed, fibre-rich foods are affordable and available in environments dominated by convenience-led UPFs.
At Nutricomms, we see this study as evidence that the future of nutrition guidance lies in integration—not polarisation. Processing matters, but so does nutrition, accessibility, and consumer behaviour. The opportunity now is to translate these findings into clear, practical communication that empowers healthier choices without oversimplification.
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