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Systematic review

Review of 27 trials found no clear weight loss difference, fasting versus calorie cutting

Welton and colleagues · Canadian family physician Medecin de famille canadien · 2020

Original title: Intermittent fasting and weight loss: Systematic review.

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

No difference

All 27 trials found weight loss of 0.8% to 13.0% of starting weight. Twelve studies compared fasting with calorie cutting and found equal results. Studies were small and short.

The study at a glance

Type of study
Systematic review
Who or what was studied
27 studies · overweight and obese adults
What was tested
intermittent fasting for 2 to 26 weeks (two trials lasted 1 year), vs calorie cutting or baseline weight
What it measured
The question itself: weight loss, compared with ordinary calorie cutting
Who has a stake
No disclosure in PubMed
No disclosure in PubMed.
Journal
Canadian family physician Medecin de famille canadien, 2020
Source
PubMed record 32060194. This page is based on the abstract only.

How much this study counts

  • •Sums up 27 studies found with a set search method, without pooling the numbers.
  • ✓Measured the question itself: weight loss, compared with ordinary calorie cutting.
  • •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

This paper is not on the ladder. It is a systematic review, and reviews and opinion pieces discuss studies that are already counted on the steps below.

↑ Stronger evidence

  1. Trials in people: weight loss

    9

    5 benefit, 2 mixed, 2 no difference

  2. Trials in people: other measures

    8

    4 benefit, 3 mixed, 1 no difference

  3. Trials in people: lab tests or safety

    1

    1 benefit

  4. Population studies

    0

    None among the papers we read.

  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 “Does intermittent fasting help with weight loss?”

Yes, but about like calorie cutting.

Confidence: moderate. Based on 26 on-topic papers.

Read the full answer

Other reviews on this question

See all 26 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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