RCT2019 · Cell Metabolism · Hall KD et al. (NIH)
Hall: an ultra-processed diet causes +500 kcal of overeating a day — inpatient RCT
Who, how long
20 healthy adults, 4 weeks resident at the NIH clinical centre, crossover design
What they found
Two weeks of ultra-processed and two of unprocessed food, matched for calories, sugar, fat, fibre and macronutrients, eaten ad libitum. During the UPF period participants ate 508 kcal more per day, ate faster, and gained 0.9 kg; on unprocessed food they lost 0.9 kg.
⚠ Caveat
Small sample, short duration, artificial setting; the mechanism (energy density, eating rate, protein dilution, flavour enhancers) can't be separated. It remains the field's only controlled feeding RCT.
Related in the knowledge base
Last reviewed: 6 September 2026
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