Ultraprocessed or minimally processed diets following healthy dietary guidelines on weight and cardiometabolic health: a randomized, crossover trial

Samuel J Dicken^{1

2

3}, Friedrich C Jassil^{4

5

6

7}, Adrian Brown^{4

5

6}, Monika Kalis⁴, Chloe Stanley^{4

5}, Chaniqua Ranson⁸, Tapiwa Ruwona^{4

5}, Sulmaaz Qamar⁴, Caroline Buck⁹, Ritwika Mallik^{4

5}, Nausheen Hamid^{4

6}, Jonathan M Bird^{5

10}, Alanna Brown^{4

5}, Benjamin Norton^{4

11}, Claudia A M Gandini Wheeler-Kingshott^{12

13

14}, Mark Hamer^{5

10}, Chris van Tulleken¹⁵, Kevin D Hall¹⁶, Abigail Fisher^{9

5}, Janine Makaronidis^{4

5

17}, Rachel L Batterham^{4

5

6}

Affiliations

¹ Centre for Obesity Research, Division of Medicine, University College London (UCL), London, UK. samuel.dicken.20@ucl.ac.uk.
² Department of Behavioural Science and Health, University College London, London, UK. samuel.dicken.20@ucl.ac.uk.
³ University College London Hospital (UCLH) Biomedical Research Centre, National Institute for Health Research, London, UK. samuel.dicken.20@ucl.ac.uk.
⁴ Centre for Obesity Research, Division of Medicine, University College London (UCL), London, UK.
⁵ University College London Hospital (UCLH) Biomedical Research Centre, National Institute for Health Research, London, UK.
⁶ Bariatric Centre for Weight Management and Metabolic Surgery, University College London Hospital (UCLH), London, UK.
⁷ Service of Endocrinology, Diabetology, Nutrition and Therapeutic Education, Department of Medicine, Geneva University Hospitals, Geneva, Switzerland.
⁸ Pain Management Centre, The National Hospital for Neurology and Neurosurgery, London, UK.
⁹ Department of Behavioural Science and Health, University College London, London, UK.
¹⁰ Institute of Sport Exercise and Health, Division of Surgery and Interventional Science UCL, London, UK.
¹¹ Digestive Disease and Surgery Institute, Cleveland Clinic London, London, UK.
¹² NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Institute of Neurology, Faculty of Brain Sciences, University College London, London, UK.
¹³ Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy.
¹⁴ Digital Neuroscience Center, IRCCS Mondino Foundation, Pavia, Italy.
¹⁵ Division of Infection, University College London, London, UK.
¹⁶ Independent Researcher, Kensington, MD, USA.
¹⁷ Department of Diabetes and Metabolism, Royal London Hospital, Barts Health NHS Trust, London, UK.

PMID: 40760353
PMCID: PMC12532614
DOI: 10.1038/s41591-025-03842-0

Randomized Controlled Trial

Ultraprocessed or minimally processed diets following healthy dietary guidelines on weight and cardiometabolic health: a randomized, crossover trial

Samuel J Dicken et al. Nat Med. 2025 Oct.

. 2025 Oct;31(10):3297-3308.

doi: 10.1038/s41591-025-03842-0. Epub 2025 Aug 4.

Authors

Affiliations

¹ Centre for Obesity Research, Division of Medicine, University College London (UCL), London, UK. samuel.dicken.20@ucl.ac.uk.
² Department of Behavioural Science and Health, University College London, London, UK. samuel.dicken.20@ucl.ac.uk.
³ University College London Hospital (UCLH) Biomedical Research Centre, National Institute for Health Research, London, UK. samuel.dicken.20@ucl.ac.uk.
⁴ Centre for Obesity Research, Division of Medicine, University College London (UCL), London, UK.
⁵ University College London Hospital (UCLH) Biomedical Research Centre, National Institute for Health Research, London, UK.
⁶ Bariatric Centre for Weight Management and Metabolic Surgery, University College London Hospital (UCLH), London, UK.
⁷ Service of Endocrinology, Diabetology, Nutrition and Therapeutic Education, Department of Medicine, Geneva University Hospitals, Geneva, Switzerland.
⁸ Pain Management Centre, The National Hospital for Neurology and Neurosurgery, London, UK.
⁹ Department of Behavioural Science and Health, University College London, London, UK.
¹⁰ Institute of Sport Exercise and Health, Division of Surgery and Interventional Science UCL, London, UK.
¹¹ Digestive Disease and Surgery Institute, Cleveland Clinic London, London, UK.
¹² NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Institute of Neurology, Faculty of Brain Sciences, University College London, London, UK.
¹³ Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy.
¹⁴ Digital Neuroscience Center, IRCCS Mondino Foundation, Pavia, Italy.
¹⁵ Division of Infection, University College London, London, UK.
¹⁶ Independent Researcher, Kensington, MD, USA.
¹⁷ Department of Diabetes and Metabolism, Royal London Hospital, Barts Health NHS Trust, London, UK.

PMID: 40760353
PMCID: PMC12532614
DOI: 10.1038/s41591-025-03842-0

Abstract

Ultraprocessed food (UPF) consumption is associated with noncommunicable disease risk, yet no trial has assessed its health impact within the context of national dietary guidelines. In a 2 × 2 crossover randomized controlled feeding trial, 55 adults in England (body mass index ≥25 to <40 kg m^-2, habitual UPF intake ≥50% kcal day^-1) were provided with two 8-week ad libitum diets following the UK Eatwell Guide: (1) minimally processed food (MPF) and (2) UPF, in a random order. Twenty-eight people were randomized to MPF then UPF, and 27 to UPF then MPF; 50 participants comprised the intention-to-treat sample. The primary outcome was the within-participant difference in percent weight change (%WC) between diets, from baseline to week 8. Participants were blinded to the primary outcome. MPF (%WC, -2.06 (95% confidence interval (CI), -2.99, -1.13) and UPF (%WC, -1.05 (95% CI, -1.98, -0.13)) resulted in weight loss, with significantly greater %WC on MPF (Δ%WC, -1.01 (95% CI, -1.87, -0.14), P = 0.024; Cohen's d, -0.48 (95% CI, -0.91, -0.06)). Mild gastrointestinal adverse events were common on both diets. Findings indicate greater weight loss on MPF than UPF diets and needing dietary guidance on food processing in addition to existing recommendations. Clinicaltrials.gov registration: NCT05627570 .

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Conflict of interest statement

Competing interests: S.J.D. receives royalties from Amazon for a self-published book that mentions UPF, payments from Red Pen Reviews as a contributor, consultancy work for Consensus and Androlabs and travel fees from a USDA National Institute of Food and Agriculture grant, (AFRI project 1033399) for a workshop on food processing classifications. R.L.B. reports honoraria from Novo Nordisk, Eli Lilly, Medscape, ViiV Healthcare and International Medical Press and advisory board and consultancy work for Novo Nordisk, Eli Lilly, Pfizer, Gila Therapeutics, Epitomee Medical and ViiV Healthcare and from May 2023 is an employee and shareholder of Eli Lilly and Company. A.B. declares researcher-led grants from Novo Nordisk and honoraria from Novo Nordisk, Lilly, Office of Health Improvement and Disparity, Johnson and Johnson and Obesity UK outside the submitted work and is on the Medical Advisory Board and shareholder of Reset Health Clinics Ltd. C.A.M.G.W.-K. is a shareholder in Queen Square Analytics. J.M. reports institutional funding from Novo Nordisk, Rhythm Pharmaceuticals and Innovate UK outside the submitted work. C.v.T. receives royalties for a book on UPF and has been paid for other broadcasting on this subject (podcast and BBC documentaries). B.N. reports honoraria from Cook Medical, and research support from Aqua Medical. The other authors declare no competing interests.

Figures

**Fig. 1. UPDATE study design, measurement timepoints and CONSORT diagram.**
a, UPDATE study design and measurement timepoints. b, Consolidated Standards of Reporting Trials (CONSORT) diagram.

**Fig. 2. Percent weight change on MPF and UPF diets.**
Estimated marginal means and s.e. values computed from mixed-effects models adjusted for randomization arm and nightshift status, with an interaction term for diet and randomization arm and a random effect for participant; ITT N = 50. a, The %WC on MPF and UPF diets from estimated marginal means. b, Difference in %WC between MPF and UPF diets from estimated marginal means; two-sided t statistic (degrees of freedom, 46.1), Cohen’s d, −0.48 (95% CI, −0.91, −0.06); P = 0.024, not adjusted for multiple comparisons. c, Difference in %WC between MPF and UPF diets from repeated-measures mixed-effects model estimated marginal means. d, Unadjusted %WC on the minimally processed diet for each participant. e, Unadjusted %WC on the UPF diet for each participant.

**Fig. 3. Changes in fasted and fed subjective appetite VAS at week 8 from baseline on MPF and UPF diets.**
Estimated marginal means and s.e. computed from mixed-effects models adjusted for randomization arm and nightshift status, with an interaction term for diet and randomization arm, interaction term for diet and time at visit (0, 15, 30 min) and a random effect for participant; ITT N = 50. Minute 0, fasted; minutes 15 and 30, fed.

**Extended Data Fig. 1. Primary outcome order effect, percentage weight change presented by (a) diet order and (b) randomisation arm.**
Estimated marginal means and standard errors computed from mixed-effects models adjusted for randomisation arm and night-shift status, with an interaction effect for diet and randomisation arm, and a random effect for participant. Abbreviations: MPF: minimally processed food; UPF: ultra-processed food. Intention-to-treat N = 50.

See this image and copyright information in PMC

References

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Ultraprocessed or minimally processed diets following healthy dietary guidelines on weight and cardiometabolic health: a randomized, crossover trial

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Ultraprocessed or minimally processed diets following healthy dietary guidelines on weight and cardiometabolic health: a randomized, crossover trial

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