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Is Metabolic Health More Important Than Weight?

A 44-study meta-analysis finds poor metabolic health predicts heart risk at least as strongly as weight category — but with caveats about pooled data.

A large new synthesis finds metabolic health predicts heart risk at least as strongly as weight category — but that comparison is not a formal head-to-head test, and “metabolically healthy obesity” still carries excess risk.

A new meta-analysis of 44 long-term cohort studies finds that adults with unhealthy metabolic numbers carried substantially higher cardiovascular risk than adults with healthy numbers, and the pattern held even at a normal body weight: a hazard ratio of 1.66 (95% CI 1.48-1.87) for cardiovascular disease. Those metabolically unhealthy normal-weight participants often did worse than participants with obesity but healthy metabolic numbers, the authors report. That comparison is a narrative summary across separate pooled groups, not a formal head-to-head statistical test. The pooled estimates also carry extreme between-study heterogeneity, and earlier meta-analyses found that “metabolically healthy obesity” still carried excess risk — so a fair reading is that metabolic health adds information beyond body weight, not that weight stops mattering.

What this means

In this synthesis, poor metabolic health predicted heart-disease risk at least as strongly as weight category did, and people with both problems carried the highest risk. Read the comparison as group averages from long-term cohort studies, not an individual verdict. The “metabolic health beats obesity” framing is a narrative summary, not a formal head-to-head test; the pooled numbers come with extreme between-study heterogeneity; and earlier meta-analyses found that metabolically healthy obesity still carries excess cardiovascular risk.

What the new analysis found

The analysis, published in the International Journal of Obesity, pooled 51 publications covering 44 longitudinal cohort studies of adults, searching PubMed and Scopus through January 2025. Each study sorted participants into one of six groups by crossing weight category with metabolic health — “metabolically healthy” meaning high blood pressure, high blood sugar and abnormal blood lipids were absent. Metabolically healthy normal weight was the reference group.

Against that reference, metabolically unhealthy obesity carried roughly double the cardiovascular disease risk (hazard ratio 2.10, 95% CI 1.85-2.40), with similarly elevated risks for heart attack (HR 2.20, 95% CI 1.75-2.76), heart failure (HR 2.05, 95% CI 1.65-2.54), coronary heart disease (HR 1.97, 95% CI 1.71-2.27) and stroke (HR 1.55, 95% CI 1.38-1.78).

The finding behind the headline is narrower but harder to dismiss. Adults whose metabolic numbers were poor despite a normal body weight had a cardiovascular disease hazard ratio of 1.66 (95% CI 1.48-1.87) — about two-thirds above their metabolically healthy normal-weight peers — and a coronary heart disease hazard ratio of 1.59 (95% CI 1.38-1.83). A normal weight did not insulate them.

nothing in the text says whether the difference is statistically reliable…

A summary, not a test

Every phenotype was measured against the same reference group, not against one another. The claim that metabolic health is the stronger determinant rests on the authors’ report that associations for metabolically unhealthy normal-weight participants often exceeded those for metabolically healthy obese participants — a narrative sentence in the abstract. The accessible text contains no pooled estimate for metabolically unhealthy normal weight versus metabolically healthy obesity, and no formal interaction test between weight category and metabolic health.

Two numbers come closest to that comparison. For coronary heart disease, metabolically unhealthy normal weight sat at HR 1.59 (95% CI 1.38-1.83) while metabolically healthy obesity sat at HR 1.44 (95% CI 1.25-1.67). Those intervals overlap, and nothing in the accessible text says whether the difference is statistically reliable. A synthesis describing a pattern across its own subgroup results is not the same as a study designed to answer the question directly.

Weight category still tracked risk

If poor metabolic health predicts heart risk at least as strongly as weight does, the easy conclusion is that weight is irrelevant. The same paper argues against that. Metabolically healthy overweight participants still carried modestly elevated cardiovascular disease risk relative to healthy normal weight (HR 1.16, 95% CI 1.06-1.28; coronary heart disease HR 1.16, 95% CI 1.08-1.23). The authors also report a positive dose-response: risk rose with higher BMI as well as with poorer metabolic health across the outcomes they studied.

Earlier work points the same way. A 2020 meta-analysis of 23 prospective cohorts (4,492,723 participants) found cardiovascular disease risk was raised in metabolically healthy overweight adults (relative risk 1.34, 95% CI 1.23-1.46) and higher still in metabolically healthy obesity (RR 1.58, 95% CI 1.34-1.85). Healthy obesity was not a free pass there either.

Statistical heterogeneity is extreme

The pooled estimates are unstable in ways a single number cannot show. For many of the analysis’s Sidik-Jonkman random-effects pools, I² — the share of variation between studies that chance alone would not explain — exceeded 90 percent: 97.5 percent for cardiovascular disease in metabolically unhealthy normal weight, 94.1 percent for cardiovascular disease in metabolically healthy overweight, and 95.8 percent for coronary heart disease in metabolically healthy obesity.

Reported DerSimonian-Laird values showed far less inconsistency in some pools — cardiovascular disease in metabolically healthy overweight fell from I² 94.1 to 41.9 percent — but not in every pool, so how inconsistent these results look partly depends on the pooling method. The supplement’s GRADE notes and its trim-and-fill table also flag publication bias: the Egger test was significant in at least four pools, and while trimming shifted the cardiovascular disease estimate for metabolically unhealthy normal weight by less than 2 percent (1.66 to 1.63), it moved several other pooled estimates considerably — for example, the metabolically unhealthy normal-weight coronary heart disease estimate fell from 1.59 to 1.43. Studies used varying definitions of “metabolically healthy” — counting different numbers of the same conditions — pooled prospective with retrospective cohorts, and characterized metabolic health from measurements taken at a single baseline assessment in most included studies.

The labels describe groups, and they shift

Even measured perfectly, the phenotype labels would not be verdicts about individuals. A 2024 review of 17 meta-analyses concluded that metabolically healthy obesity may be only a transient condition and still carries increased risk of type 2 diabetes, cardiovascular disease, cancer, chronic kidney disease and depressive syndrome. A 2016 meta-analysis of 22 prospective studies found that whether metabolically healthy obesity looks risk-free depends on which criteria define “healthy,” which makes the definition itself part of the result. We have covered that practical end before: diet and exercise can put type 2 diabetes into remission in some people (can-diet-and-exercise-reverse-type-2-diabetes).

What we could not check

At press time we had the abstract, the reference list, and a public supplement that includes subgroup tables, a per-study risk-of-bias assessment (ROBINS-I), GRADE assessments and a trim-and-fill table. We did not independently re-derive the per-study risk-of-bias judgments or the pooling, and we do not report funding or grant numbers because they were not visible in the accessible text. The authors declare no competing interests.

Terms explained

  • Metabolically healthy obesity (MHO) — a body mass index at or above 30 kg/m² without the metabolic risk factors, such as high blood pressure, high blood sugar or abnormal blood lipids, that commonly accompany obesity.
  • Metabolically unhealthy normal weight (MUNW) — a body mass index in the normal range with one or more of those risk factors present.
  • Body mass index (BMI) — weight in kilograms divided by height in meters squared. The studies here used it to define weight category.
  • Hazard ratio (HR) — the rate of new cases in one group divided by the rate in a reference group over the same follow-up period. An HR of 2.10 means about twice the rate of new diagnoses in that group, not a doubling of any individual’s personal risk.
  • 95% confidence interval (CI) — the range of values statistically compatible with the observed estimate. An interval that stays above 1.0 indicates the elevated risk is unlikely to be a chance finding.
  • Heterogeneity (I²) — the percentage of variation among study results beyond what chance alone would produce. Very high values mean the individual studies disagree substantially and the single pooled number hides that spread.

Sources

  1. Ghorbani Z, Soltani S, Aune D, Khandouzi N, Noormohammadi M, Kazemi A. Metabolic health is a stronger determinant than obesity for cardiovascular disease incidence: a meta-analysis of longitudinal cohort studies. International Journal of Obesity, published online 2026-10-17. https://doi.org/10.1038/s41366-026-02237-6 — paper page: https://www.nature.com/articles/s41366-026-02237-6
  2. Opio J, Croker E, Odongo GS, Attia J, Wynne K, McEvoy M. Metabolically healthy overweight/obesity are associated with increased risk of cardiovascular disease in adults, even in the absence of metabolic risk factors: A systematic review and meta-analysis of prospective cohort studies. Obesity Reviews 2020;21(12):e13127. https://doi.org/10.1111/obr.13127
  3. Eckel N, Meidtner K, Kalle-Uhlmann T, Stefan N, Schulze MB. Metabolically healthy obesity and cardiovascular events: A systematic review and meta-analysis. European Journal of Preventive Cardiology 2016;23(9):956-966. https://doi.org/10.1177/2047487315623884
  4. Čermáková E, Forejt M. Metabolically healthy obesity and health risks – a review of meta-analyses. Central European Journal of Public Health 2024;32(1):3-8. https://doi.org/10.21101/cejph.a7806
  5. Nutritious News: Can diet and exercise reverse type 2 diabetes? https://nutritiousnews.com/2026/10/06/can-diet-and-exercise-reverse-type-2-diabetes/

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