How big someone’s waist measures is a genetically influenced marker of central body fat, mapped by the same large study that built this site’s hip circumference page — plus two further studies whose loci only show up once smoking or physical activity is accounted for.
What this condition connects to
Solid lines are connections this site curates. Dashed lines mean the two ends share a research paper — worth knowing, and not a claim that one explains the other.
Prevalence
Not a categorical condition with a prevalence figure. Waist circumference is a continuous trait studied in up to 241,258 people across the three studies behind this page (Shungin et al. 2015, PMID:25673412; Justice et al. 2017, PMID:28443625; Graff et al. 2017, PMID:28448500).
Inheritance
Polygenic: 44 variants on this site from three separate studies with three different analytic designs — a baseline discovery meta-analysis, a gene-by-smoking interaction model, and a gene-by-physical-activity interaction model. Two genes here (LCORL, CDK6) are independently linked to height elsewhere on this site.
Waist circumference — measured with a tape at the narrowest point of the torso, usually near the navel — is a marker of central, abdominal fat. It predicts cardiometabolic risk in ways that overlap with, but are not identical to, body mass index, which is part of why clinical guidelines for metabolic syndrome use it as its own measurement rather than deriving it from weight and height alone.
The same joint study behind hip circumference
Shungin et al. 2015 ran a meta-analysis of up to 224,459 people and found 49 loci for waist-to-hip ratio adjusted for BMI, plus a further 19 loci specifically for waist and hip circumference measures on their own. This site's hip circumference page already covers that study's hip-specific half; these 18 variants are its waist-specific counterpart. Among them is rs2745353, near RSPO3 — one of the most consistently replicated genes in body-fat-distribution genetics across multiple independent studies, here showing up again for the waist measurement specifically. The same study also anchors this site's waist-to-hip ratio page, for the ratio itself rather than either measurement alone.
Where smoking changes the picture
Justice et al. 2017 analysed 241,258 people (51,080 current smokers, 190,178 nonsmokers), using a model that jointly tests an ordinary genetic effect alongside a gene-by-smoking interaction — built specifically to catch loci whose effect on body fat distribution only shows up once smoking status is accounted for. The study found 23 novel loci across BMI, waist circumference and waist-to-hip ratio combined; 11 of them were specifically for waist circumference, the set on this page. Two of the genes here, LCORL and CDK6, are already established height-associated genes elsewhere on this site's height page — the same locus doing double duty across two unrelated anthropometric traits, a real and fairly common pattern in this kind of genetics rather than a coincidence worth dismissing.
Where physical activity changes the picture
Graff et al. 2017 — the same paper already discussed on this site's obesity page for its physical-activity-by-FTO interaction finding — analysed 200,452 adults with a parallel design: a joint test of a main genetic effect and a gene-by-physical-activity interaction. FTO itself was the only locus in the whole study to reach genome-wide significance for the interaction term specifically; the 15 waist-circumference variants on this page (9 from the general model, 6 more from a physically-active-only subgroup analysis) were identified or confirmed within that broader physical-activity-adjusted analysis, not each individually shown to interact with activity level the way FTO was.
Clinical detail
What is actually diagnosed and treated here
Waist circumference is measured directly with a tape measure, not inferred from genotype. Clinical criteria that use waist circumference, such as metabolic syndrome definitions, rely on the measurement itself; none of the 44 variants on this page is used to interpret it.
The genuinely useful part of this page is what the three studies together show about mechanism: some genetic effects on body fat distribution are constant, and some only appear once smoking status or physical activity level is taken into account. That is a real finding about how genes and environment interact, not a personal test result — none of these variants tells an individual whether smoking or exercise will change their own waist measurement.
Related variants MyGeneLog™ checks for
What a 23andMe/AncestryDNA export or raw VCF can and can't tell you about Waist Circumference comes down to these specific, well-studied positions — not a diagnosis. 58 positions are linked to this page; the ones this page's own text discusses are shown first.
PLoS genetics · 2017 · PMID 28448500 · open access
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Questions about Waist Circumference
What is waist circumference?
Waist circumference is a measurement taken with a tape measure at the narrowest point of the torso, usually near the navel, used as a marker of central abdominal fat independent of overall body weight.
Is waist circumference the same as waist-to-hip ratio?
No. Waist-to-hip ratio is waist circumference divided by hip circumference — a measure of body shape. Waist circumference alone is just the one measurement, and this site keeps them as separate pages for that reason.
Does smoking or exercise actually change how these genes affect waist size?
For most of the loci here, that has not been directly shown — only FTO, in the physical-activity study, reached genome-wide significance for the interaction itself. The rest were found or confirmed within models built to detect that kind of effect, which is a narrower claim than showing each one individually interacts with smoking or activity.
Why does the LCORL gene show up here when it is also linked to height on this site?
The same genetic locus affecting more than one unrelated trait is a real and fairly common pattern in this kind of genetics, not a coincidence or an error — LCORL and CDK6 are established height genes that also turned up in this waist-circumference study.
Free to reuse. This page's text is original writing from freely-available research, licensed CC BY 4.0 — reuse it, including commercially, with attribution to MyGeneLog™. It's general research-derived information, not medical advice or a diagnosis — see Terms of Use.