Ultra-processed food is a big part of many modern diets, and it is easy to assume that cutting it is the obvious fix. A randomized trial in England tested that idea directly, against a diet that also followed national healthy-eating guidance. The answer was not a simple yes or no.
What the trial compared
Fifty-five adults with a body mass index from 25 to under 40, who got at least half their daily calories from ultra-processed food, took part. Each person ate two diets for eight weeks each, in random order. Both followed the UK Eatwell Guide, the national healthy-eating model. One diet was built on minimally processed food. The other was built on ultra-processed food. People could eat as much as they wanted.[1]
Fifty of the 55 were included in the main analysis, which keeps people in the group they were assigned to. Participants were blinded to the main outcome, percent change in body weight.[1]
What happened to weight
Both diets led to weight loss. On the minimally processed diet, weight fell by 2.06% on average. On the ultra-processed diet, it fell by 1.05%. The gap between them was about one percentage point (95% confidence interval 0.14 to 1.87 points), in favour of the minimally processed diet, so the true gap could be small. The difference was statistically significant (P = .024).[1]
Mild stomach side effects were common on both diets.[1]
What happened to blood sugar and cholesterol
Two blood markers changed on the ultra-processed diet only. Compared with baseline, fasting glucose and LDL cholesterol were lower after that diet, and not after the minimally processed one. The paper reports these as secondary results.[1] These were secondary measures, so treat this as a finding to note, not a conclusion. The trial does not test whether food type matters beyond the two diets it compared.
What this does and does not show
It is one trial, eight weeks long, with 50 people analysed. Participants had a body mass index from 25 to under 40. The authors conclude that people following healthy-eating guidance may also need advice on food processing, on top of the guidance they already have.[1]
It does not show what happens over years or test any disease outcome, and it describes weight change, not long-term health. If you have a medical condition or take regular medication, talk with your clinician before you change your diet in a major way.
References
[1] Dicken SJ, Jassil FC, Brown A, Kalis M, Stanley C, et al. Ultraprocessed or minimally processed diets following healthy dietary guidelines on weight and cardiometabolic health: a randomized, crossover trial. Nature Medicine. 2025 Aug 4;31(10):3297–3308. DOI: 10.1038/s41591-025-03842-0. Registration NCT05627570. Finding: 2×2 crossover trial, 55 adults in England (50 in the intention-to-treat analysis), two 8-week ad libitum diets following the UK Eatwell Guide; percent weight change −2.06% (minimally processed) vs −1.05% (ultra-processed), difference −1.01% (95% CI −1.87 to −0.14), P = 0.024; fasting glucose and LDL-C lower on the ultra-processed diet only; mild GI adverse events common on both. ↑︎ a b c d e f
This post is based on the full open-access text of one trial. Other studies on the topic were not included because their full texts were not available to me.
Kurt Greiner
Kurt is a digital strategist and IT professional blending emerging technology with practical application, exploring how individuals can leverage modern tools to navigate the second half of life with purpose.
Leave a Reply