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Testing ultra-processed food and fullness-hormone responses

A preliminary 14-day controlled feeding trial found that a ~95% ultra-processed diet left GLP-1, PYY, ghrelin and PP responses unchanged in lean young adults — an exploratory, industry-partnership-funded null.

A controlled 14-day trial found a ~95% ultra-processed diet left fullness-hormone responses unchanged in lean young adults — a bounded null. Satiety hormones were not significantly disrupted in a short, controlled crossover study.

What this means

In a tightly controlled feeding trial, two weeks of almost entirely ultra-processed food did not change lean young adults’ fullness-hormone responses to a fixed test meal. The null is bounded — lean young adults who rarely ate ultra-processed food, a 14-day exposure, an exploratory analysis, industry-partnership funding — so it neither disproves the fullness-hormone idea nor clears ultra-processed food.

The study

Does a high ultra-processed diet disrupt the hormones that signal fullness? A preliminary controlled test of that idea — a secondary analysis published September 24 in the European Journal of Nutrition — came back empty. In the crossover Restructure trial (registered NCT06113146), lean young adults (average age 27, BMI about 23.6) who habitually ate little ultra-processed food spent two 14-day stretches on diets deriving roughly 95% of calories from ultra-processed products, separated by a washout. Around each stint, the 32 participants with blood samples ate a fixed-calorie test meal (552 kcal) while researchers tracked the gut hormones GLP-1, PYY, PP and ghrelin over three hours.

Nothing changed: no post-meal hormone response differed after either ultra-processed stint (all p>0.05). Appetite ratings shifted slightly overall — more hunger, less fullness versus participants’ usual diets (p=0.002 and p<0.0001) — but no single timepoint differed, and the authors call the changes small; morning fasting ratings held stable. One fasting measure, PYY, ran 17% higher after one ultra-processed diet — the opposite direction from hormone-blunting.

The boundaries are the story. Each person’s own free-living diet, not a controlled low-ultra-processed regime, served as the comparison — a limitation the authors name. The trial was built around its energy-intake question, so this satiety analysis is exploratory. And 14 days in lean young adults cannot speak for people with obesity or long-term high-UPF eaters. The null therefore cuts both ways: it complicates the mechanistic story beneath this week’s observational wave linking ultra-processed food to heart problems, and it does not prove ultra-processed food harmless. Funding came from a Dutch public-private food partnership (TKI Agri & Food); the senior author discloses extensive ties to food companies including Ajinomoto, Ferrero, PepsiCo, Mondelez and the industry group ILSI Europe.

Terms explained

  • Gut appetite hormones (GLP-1, PYY, PP, ghrelin): GLP-1, PYY and PP are released after eating — the first two by the gut, PP by the pancreas — and promote feelings of fullness; ghrelin, made mainly in the stomach, rises before meals and drives hunger. Here, all four were measured in blood around a standardized meal, alongside fasting samples.
  • Crossover trial: every participant completes each diet in turn, in randomized order, with a rest period (washout) between — so each person effectively serves as their own comparison.
  • Ultra-processed food (NOVA category 4): the most heavily processed tier of the widely used NOVA classification — industrially formulated products built largely from refined ingredients and additives rather than whole foods.

Sources

  1. van Bruinessen M, Liu Z, Heuven LAJ, Stieger M, Lasschuijt MP, Forde CG. “Satiety responsiveness following dietary exposure to ultra-processed foods differing in texture-derived eating rate: a secondary analysis of a randomized controlled crossover diet intervention.” European Journal of Nutrition (Springer), published 2026-09-24 (Eur J Nutr 65(7):261). Open access (CC BY 4.0). https://doi.org/10.1007/s00394-026-04111-7 · DOI: 10.1007/s00394-026-04111-7 · PMID: 42782361
  2. Parent trial registration, Restructure trial: ClinicalTrials.gov NCT06113146. https://clinicaltrials.gov/study/NCT06113146 · Registry primary outcome: average daily energy intake (satiety a registered secondary outcome).

Funding/COI (from the paper, as recorded in the packet): funded by the Dutch TKI Agri & Food public-private partnership project “Restructure” (TKI 22.150) on food texture and eating rate; registry collaborator Next Food Collective. C.G. Forde discloses research support from Ajinomoto, Ferrero (Somartec), Tate & Lyle and TKI; an ILSI Europe scientific committee seat, plus committee seats with Lesaffre and IAFNS; travel/fees from Kerry, USDA, ILSI, Ajinomoto, British Nutrition Society, Nestlé Nutrition Institute, AB Mauri, IAFNS, World Sugar Research Organization and the Northern Irish Dairy Council; and speaking fees from Ferrero, PepsiCo, General Mills and Mondelez. M.P. Lasschuijt reports Nestlé Nutrition Institute speaking/travel fees. Other authors: none declared.

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