Same calories, same nutrients. The ultra-processed meal still raised insulin more.

People say: “A calorie is a calorie, however it's made” We read the study.

What they did

Randomised controlled trial (RCT). 32 people. one meal per session, measured for 3 hours after eating (two sessions on separate days); fMRI on a separate day.

A trial. Chance decided who did what.

Who: Healthy-weight adults aged 18-45 in Roanoke, Virginia, USA (57 enrolled; mean age 26.2, mean BMI 22.75, 31.6% men, 68% white). 32 did both metabolic sessions (31 for insulin); 52 analysed in the fMRI part; 29 in the metabolism-brain link analysis

What they found
  • Blood sugar, 3 hourssameno clear change
  • Insulin after eatinghigher40 to 120 minutes
  • Liking and hungersameno clear change
The catch

More to know, from our read of the paper:

  • One meal only (~300 kcal), eaten in a lab after an overnight fast: says nothing about long-term health, weight or diabetes. Authors: 'this study was not designed to assess chronic outcomes'
  • Small: 32 people in the meal part; young (mean 26), healthy-weight, no metabolic disease. May not apply to older people or people with overweight or diabetes
  • Meals were matched on weight, energy, energy density, carbs, fat, protein, available carbs, glycaemic index and load, fibre, sodium and water (all <1.6% apart), but protein sources differed and the UPF meal had more additives; food matrix not measured. A 12 g serving of water was added to the UPF meal to match weight
  • The UPF meal was eaten 1.5 min more slowly on average (authors: unlikely to matter physiologically)
  • Metabolic rate AUC was HIGHER after the UPF meal (body used slightly more energy), and fat oxidation higher / carbohydrate oxidation lower. Don't spin 'more fat burning' as good or bad; the authors read the delayed carb shift as resembling a pattern seen in insulin resistance (interpretation, not tested)
The verdict

Same nutrients, different response. One meal, though.

In short

32 healthy young adults (average age 26) ate two meals of about 300 calories on separate days, in random order: one ultra-processed, one not, matched on calories, carbs, fat, protein, fiber, salt and glycaemic index. Over the next 3 hours, total blood sugar was about the same, but insulin was clearly higher after the ultra-processed meal. People liked both meals equally and were just as hungry. This was one meal in healthy-weight adults, so it says nothing yet about long-term health.

The video
The paper

Hutelin Z, Ahrens M, Baugh ME, Nartey E, Herald DL III, Hanlon AL, DiFeliceantonio AG (2026). Metabolic and neural responses to ultraprocessed foods: a randomized, controlled, crossover study. Nature Metabolism.

Design: Randomised controlled trial (RCT) · randomized crossover trial (each person ate both meals, on separate days, in random order) of one ~300 kcal ultraprocessed vs non-ultraprocessed meal, nutritionally matched; plus an fMRI food-picture auction task. Acute single-meal study (3 h after eating), not a diet trial

DOI: 10.1038/s42255-026-01619-4

Goals:

Eat better
How we checked

We read the abstract and the full text of this paper and checked every number on this page against it (17 facts, checked on 2026-10-29). The study design is named above. Cohort and other observational studies are described as linked, not proven. Found an error? Email theis@onestudyaday.com.

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