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Diet and food › Ultra-Processed Food › Studies

Randomized trial · measured lab tests or safety

Trial in 34 adults: waist fell in both groups, gut bacteria differed

de Oliveira and colleagues · Food & function · 2025

Original title: Effects of dietary energy restriction of ultra-processed foods compared to a generic energy restriction on the intestinal microbiota of individuals with obesity: a secondary analysis of a randomized clinical trial.

Under review. A person has not yet checked this summary against the paper. It is written from the PubMed abstract. Until a person checks it, search engines are asked not to list this page.

What the study found

Mixed

Waist size and body fat fell in both groups. Gut bacteria family Ruminococcaceae rose more in the group limiting ultra-processed food (p-interaction = 0.03).

The study at a glance

Type of study
Randomized trial
Who or what was studied
34 people · 34 adults with obesity who finished the trial (43 started)
What was tested
Calorie cut plus limiting ultra-processed food to 5% of intake vs a general calorie cut, for 6 months
What it measured
Lab tests or markers
How long
26 weeks
Who has a stake
No disclosure in PubMed
No disclosure in PubMed.
Journal
Food & function, 2025
Source
PubMed record 40977640. This page is based on the abstract only.

How much this study counts

  • ✓Randomized: people were put into groups by chance, so the groups start out alike.
  • –Small: 34 people. Small trials can miss real effects or find chance ones.
  • •Lasted 26 weeks.
  • –Measured lab tests or markers, which stand in for death, heart disease, diabetes and cancer. A better marker does not always mean better health.
  • •The PubMed record has no conflict-of-interest statement.
  • •Summarized from the PubMed abstract only. The full paper may hold details the abstract leaves out.

✓ Strength– Limit• Note

These points come from fixed rules about the type of study, its size and length, what it measured, and who has a stake. Every study on Digestery gets the same rules.

Where this study sits

Each dot is one on-topic paper on this question. Steps near the top answer the question more directly.

↑ Stronger evidence

  1. Trials in people: death and chronic disease

    2

    1 no difference, 1 harm

  2. Trials in people: other measures

    3

    1 mixed, 1 no direction, 1 harm

  3. Trials in people: lab tests or safety

    1

    1 mixed

    ↑ This study is the ringed dot

  4. Population studies

    17

    1 mixed, 16 harm

  5. Blood levels and genes

    0

    None among the papers we read.

↓ Weaker evidence

  • Points to benefit
  • Mixed
  • No difference
  • No direction
  • Points to harm

How it fits with the other research

The short answer to “Are ultra-processed foods bad for your health?”

Linked to worse health; cause not proven.

Confidence: low. Based on 38 on-topic papers.

Read the full answer

Few other papers sit on the same step, so there is little to compare it with.

  • Counted on the ladder, but not quoted in the page’s main findings.

Other papers on the same step

None among the papers we read.

See all 38 studies on this question

How this page was made

Label

First read of the abstract
Claude Sonnet
Independent second read
Claude Haiku
Differences settled
The two reads agreed on every checked field. Claude Opus 5.5.
Headline
Claude Sonnet, from the checked study record. A script checked its numbers and wording.
Numbers
Checked against the abstract by a script
“How much this study counts”
Fixed rules, the same for every study
Source check by a person
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