Study analysis · Obesity Surgery · 2005
Thin people could have MORE dangerous fat than obese people — here's why.
Deep belly fat has more unhealthy trans fats than other fat, even in people who aren't overweight.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
In simple terms
This study looked at how much trans fat was stored in different kinds of belly fat in people who had surgery. It found that trans fat was more common in the deep belly fat than the fat under the skin, but it didn't show that eating trans fat makes you fat — it just showed where the fat ended up.
What’s the bottom line?
Scientists checked the fat inside people's bellies after surgery and found that the deep belly fat had more unhealthy trans fats than the fat under the skin.
How strong is this study?
The scientists measured the fat carefully, which is good. But they didn't ask people what they ate or control for other things like exercise, so we can't be sure why the fat was there. That means we should be careful trusting any big claims about what causes what.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
19 / 100
- Randomizationnot randomized
- Blindingblinding unclear
- Control group+15/15
- Sample sizeno sample size reported
- Follow-upno follow-up reported
100 / 100
23 / 100
- P-values+15/15
- Effect sizeno effect size reported
- Confidence intervalsno confidence intervals
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 532 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
This design cannot establish causation — the findings describe an association, not a cause. This is a cross-sectional study that measures fat composition at a single point in time; it cannot determine whether higher trans fatty acid levels in visceral fat cause metabolic changes or are the result of them. Temporal sequence and control of confounders are not established.
No Conflicts
No conflicts of interest identified
No conflicts of interest or funding sources were disclosed; all authors are affiliated with academic institutions without apparent industry ties.
The study lacks a formal conflict of interest statement or funding disclosure. However, all authors are affiliated with public academic institutions in Brazil (UFRGS and PUCRS), with no indication of industry employment, funding, or financial relationships. The absence of disclosure does not imply conflict, but transparency is limited.
Key takeaways
- 01
Deep belly fat had 8.7% trans fats in obese people and 9.3% in non-obese people — higher than other fat types (6.3–6.9%).
- 02
Yes — this means even thin people can have high levels of unhealthy trans fats in their most dangerous fat, which is linked to heart disease and diabetes.
Surprising findings
- Non-obese individuals had higher visceral TFA levels (9.3%) than obese individuals (8.7%).People assume obesity correlates with higher toxin or fat accumulation — but here, the lean group had more of the most harmful fat in the most dangerous location.
- Trans fat levels in abdominal fat were nearly double the previously reported global average.Prior studies showed 3–6% TFA in fat tissue; this study found 6.3–9.3% — suggesting either dietary exposure is worse than thought, or metabolic processing differs regionally.
Practical takeaways
Avoid processed foods with 'partially hydrogenated oils' — they’re the main source of trans fats that accumulate in your most dangerous fat.
This study didn’t measure diet, so we can’t say exactly how much you ate — but the fat in your body reflects your long-term intake.
medium confidenceIf you're thin but have a big belly, get your metabolic health checked — you might have high visceral fat even without being overweight.
This study used surgical tissue samples — not a general population. But it aligns with other research on visceral fat risks.
medium confidenceWhy this study matters
Visceral Fat Is a Trans Fat Magnet
Visceral fat contained 8.7% trans fatty acids (TFA) in obese patients and 9.3% in non-obese patients — significantly higher than subcutaneous (6.9%) or retroperitoneal (6.3%) fat. This was consistent across both groups, regardless of body weight.
This means you can be thin but still have high levels of the most dangerous fat — the kind linked to heart disease and diabetes — because your body stores trans fats preferentially in your organs' surrounding fat.
Obesity Doesn't Determine Trans Fat Levels
The study found no significant difference in TFA levels in visceral fat between morbidly obese and non-obese individuals — challenging the assumption that more body fat equals more trans fat accumulation.
It flips the script: it’s not just about how much fat you have, but where it is — and what kind of fats your body has been absorbing from your diet.
Brazilian Fat Has More Trans Fats Than Global Norms
TFA levels in all fat depots (6.3–9.3%) were higher than previously reported international ranges (3–6%), suggesting Brazilians have higher dietary exposure to trans fats.
This hints at regional dietary patterns — maybe processed foods or cooking oils in Brazil contain more trans fats than in other countries.
Want the whole report?
Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists checked the fat inside people's bellies after surgery and found that the deep belly fat had more unhealthy trans fats than the fat under the skin.
Research results
Deep belly fat had 8.7% trans fats in obese people and 9.3% in non-obese people — higher than other fat types (6.3–6.9%).
What this means - more context
Yes — this means even thin people can have high levels of unhealthy trans fats in their most dangerous fat, which is linked to heart disease and diabetes.
To determine trans fatty acid (TFA) content in subcutaneous, retroperitoneal, and visceral abdominal fat of morbidly obese and non-obese patients.
Visceral fat had significantly higher TFA levels (8.7% in obese, 9.3% in non-obese) than subcutaneous or retroperitoneal fat, with no difference between obese and non-obese groups. TFA levels in all depots exceeded previously reported international ranges (6.3–9.3% vs. 3–6%).
Methods Used
Adipose tissue samples collected during abdominal surgery from morbidly obese (bariatric) and non-obese (plastic) patients; lipids extracted and TFA quantified using FTIR-ATR spectroscopy.
Main Finding
Visceral adipose tissue contained significantly higher TFA concentrations than other fat depots (P<0.001 for obese, P<0.05 for non-obese), with no significant difference between obese and non-obese groups.
Confidence Level
Moderate — direct measurement of TFA in human tissue using validated spectroscopy; however, no randomization, no control for dietary intake, and small non-random sample limit causal inference.
Study Flags
Red Flags
- •No dietary intake data collected
- •Non-random convenience sample
- •No control for confounding lifestyle factors
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Surprising Findings
Non-obese individuals had higher visceral TFA levels (9.3%) than obese individuals (8.7%).
People assume obesity correlates with higher toxin or fat accumulation — but here, the lean group had more of the most harmful fat in the most dangerous location.
Practical Takeaways
Avoid processed foods with 'partially hydrogenated oils' — they’re the main source of trans fats that accumulate in your most dangerous fat.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 532 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Human Cross-Sectional
Subject
Lower probability
on the GRADE evidence scale
This study looked at how much trans fat was stored in different kinds of belly fat in people who had surgery. It found that trans fat was more common in the deep belly fat than the fat under the skin, but it didn't show that eating trans fat makes you fat — it just showed where the fat ended up.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Clear measurement method using FTIR-ATR spectroscopy for TFA quantification
- Direct tissue sampling from multiple fat depots
- Precise anatomical separation of fat types (subcutaneous, retroperitoneal, visceral)
Weaknesses
- Cross-sectional design prevents inference of directionality or causality
- No control for dietary intake, lifestyle, or medication use
- Blinding status unknown, risking measurement bias
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists checked the fat inside people's bellies after surgery and found that the deep belly fat had more unhealthy trans fats than the fat under the skin.
Research results
Deep belly fat had 8.7% trans fats in obese people and 9.3% in non-obese people — higher than other fat types (6.3–6.9%).
What this means - more context
Yes — this means even thin people can have high levels of unhealthy trans fats in their most dangerous fat, which is linked to heart disease and diabetes.
To determine trans fatty acid (TFA) content in subcutaneous, retroperitoneal, and visceral abdominal fat of morbidly obese and non-obese patients.
Visceral fat had significantly higher TFA levels (8.7% in obese, 9.3% in non-obese) than subcutaneous or retroperitoneal fat, with no difference between obese and non-obese groups. TFA levels in all depots exceeded previously reported international ranges (6.3–9.3% vs. 3–6%).
Methods Used
Adipose tissue samples collected during abdominal surgery from morbidly obese (bariatric) and non-obese (plastic) patients; lipids extracted and TFA quantified using FTIR-ATR spectroscopy.
Main Finding
Visceral adipose tissue contained significantly higher TFA concentrations than other fat depots (P<0.001 for obese, P<0.05 for non-obese), with no significant difference between obese and non-obese groups.
Confidence Level
Moderate — direct measurement of TFA in human tissue using validated spectroscopy; however, no randomization, no control for dietary intake, and small non-random sample limit causal inference.
Study Flags
Red Flags
- •No dietary intake data collected
- •Non-random convenience sample
- •No control for confounding lifestyle factors
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Surprising Findings
Non-obese individuals had higher visceral TFA levels (9.3%) than obese individuals (8.7%).
People assume obesity correlates with higher toxin or fat accumulation — but here, the lean group had more of the most harmful fat in the most dangerous location.
Practical Takeaways
Avoid processed foods with 'partially hydrogenated oils' — they’re the main source of trans fats that accumulate in your most dangerous fat.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 532 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Human Cross-Sectional
Subject
Lower probability
on the GRADE evidence scale
This study looked at how much trans fat was stored in different kinds of belly fat in people who had surgery. It found that trans fat was more common in the deep belly fat than the fat under the skin, but it didn't show that eating trans fat makes you fat — it just showed where the fat ended up.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Clear measurement method using FTIR-ATR spectroscopy for TFA quantification
- Direct tissue sampling from multiple fat depots
- Precise anatomical separation of fat types (subcutaneous, retroperitoneal, visceral)
Weaknesses
- Cross-sectional design prevents inference of directionality or causality
- No control for dietary intake, lifestyle, or medication use
- Blinding status unknown, risking measurement bias
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
The scientists measured the fat carefully, which is good. But they didn't ask people what they ate or control for other things like exercise, so we can't be sure why the fat was there. That means we should be careful trusting any big claims about what causes what.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
19 / 100
- Randomizationnot randomized
- Blindingblinding unclear
- Control group+15/15
- Sample sizeno sample size reported
- Follow-upno follow-up reported
100 / 100
23 / 100
- P-values+15/15
- Effect sizeno effect size reported
- Confidence intervalsno confidence intervals
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 532 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
This design cannot establish causation — the findings describe an association, not a cause. This is a cross-sectional study that measures fat composition at a single point in time; it cannot determine whether higher trans fatty acid levels in visceral fat cause metabolic changes or are the result of them. Temporal sequence and control of confounders are not established.
No Conflicts
No conflicts of interest identified
No conflicts of interest or funding sources were disclosed; all authors are affiliated with academic institutions without apparent industry ties.
The study lacks a formal conflict of interest statement or funding disclosure. However, all authors are affiliated with public academic institutions in Brazil (UFRGS and PUCRS), with no indication of industry employment, funding, or financial relationships. The absence of disclosure does not imply conflict, but transparency is limited.
Standing
Who’s using this study?
The videos and claims on this site that lean on this study, and the researchers who wrote it.
1 video from Thomas DeLauer cite this study, drawing 1 claim from it.
- Contradicted
Evidence contradicts this claim.
Evidence
Authored by
7 researchersIf this is your work, this is how we attribute it on Fit Body Science. Josiane Woutheres Bortolotto is listed as the lead author.
- Universidade Federal do Rio Grande do Sul
Cited in 1 claim
- Pontifícia Universidade Católica do Rio Grande do Sul
Cited in 1 claim
- Pontifícia Universidade Católica do Rio Grande do Sul
Cited in 1 claim
- Universidade Federal do Rio Grande do Sul
Cited in 1 claim