Otherindependent cross-checkabstract checked I-GUT-114 in-depth review
Why the belly swells in bloating
Abdominothoracic mechanisms of functional abdominal distension and correction by biofeedback.
Overview
Barba E et al.. Gastroenterology 2015 · PMID 25500424 · DOI 10.1053/j.gastro.2014.12.006
In people with functional bloating, the belly swells because the diaphragm drops and the abdominal wall relaxes, not mainly because of high internal pressure.
Does the study support the specific claim? No · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Explain visible bloating.
- How was the study done?
CT and muscle recordings.
- How many people, animals or samples were studied?
45 patients.
- What was actually found?
Diaphragm descended and abdominal wall protruded; biofeedback reduced girth.
- How large was the observed effect?
Girth +32 mm; reduced 25 mm with biofeedback.
- What do the results mean in everyday life?
Bloating is uncomfortable but works through muscle reflexes.
- What are the study's limitations?
Small; no blood-flow data.
- What does it say about Elawady's specific claim?
Contradicts the aorta-compression idea.
- Do the results apply to Germany and Europe?
Universal.
- What can explicitly not be concluded from this study?
Cannot exclude rare extreme cases.
Scientific in-depth review
1. Full reference
- Authors
- Barba E et al.
- Journal
- Gastroenterology
- Year
- 2015
- Identifier
- PMID 25500424 DOI 10.1053/j.gastro.2014.12.006
- Verification
- verified – PubMed efetch 2026-10-26 + Crossref 2026-10-26
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
Non-US government support (PubMed); COI not stated in abstract
2. Research question
What mechanisms produce visible abdominal distension in functional gut disorders?
3. Study design and population
- Study design
- Other – Prospective physiological study with CT and electromyography, plus small biofeedback intervention
- Population
45 patients (42 women) with IBS-C, functional bloating or IBS-M and episodes of visible distension
- Country
Spain
- Period
Published 2015
- Sample size
45
- Inclusion and exclusion criteria
Functional disorders with discrete distension episodes
4. Methods and endpoints
- Exposure / intervention
Episodes of distension
- Comparator
Basal state; control sessions
- Endpoints
Diaphragm/intercostal EMG, CT volumes, girth
- Statistical methods
Paired comparisons
5. Actual results
- Results
Distension episodes: diaphragm descent 12 +/- 2 mm, intercostal contraction, lung volume +501 +/- 93 mL, girth +32 +/- 3 mm (all P<.001). Biofeedback reduced diaphragm and intercostal activity and girth by 25 +/- 3 mm.
- Absolute risks
Not applicable
- Authors' conclusion
Abdominal distension in functional gut disorders is a behavioural abdominothoracic response that biofeedback can reduce.
6. Strengths
- Objective imaging and EMG
7. Weaknesses
- Small, selected
- No pressure measurement
8. Risk of bias
- Orienting tool
- none applicable
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Uncontrolled physiological design for the mechanism part.
9. Assessment of the statistical interpretation
Not applicable
10. Relevance to the specific claim
Bloating-type distension largely reflects muscle reflex and diaphragm descent, not a pressure build-up that compresses the aorta and vena cava.
11. Independent contrary findings
Did not measure vascular flow.
12. Transferability to Germany and Europe
Universal.
13. Overall methodological judgement
Mechanistic evidence against the claimed pathway.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | low |
| Directness | indirect |
| Reproducibility | partly replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Haemodynamics during bloating.
15. Linked fact checks
- Bloating after meals raises intra-abdominal pressure enough to compress the aorta and inferior vena cava and to reduce blood flow to the organs. – Studies contradicting or limiting the claim