Body roundness index, thyroid hormones, and threshold effects in US adults: a cross-sectional study from NHANES
BackgroundThe correlation between visceral adipose tissue and thyroid hormones is debated, and the conventional body mass index (BMI) is insufficient for differentiating fat distribution patterns. This study investigates the nonlinear relationship and threshold effects of the Body Roundness Index (B...
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Frontiers Media S.A.
2025-07-01
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| Series: | Frontiers in Nutrition |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fnut.2025.1539022/full |
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| author | Sijia Yang Kun Liao Lu Zhou Shengbo Zhang Jianchao Wu |
| author_facet | Sijia Yang Kun Liao Lu Zhou Shengbo Zhang Jianchao Wu |
| author_sort | Sijia Yang |
| collection | DOAJ |
| description | BackgroundThe correlation between visceral adipose tissue and thyroid hormones is debated, and the conventional body mass index (BMI) is insufficient for differentiating fat distribution patterns. This study investigates the nonlinear relationship and threshold effects of the Body Roundness Index (BRI), a geometric metric of visceral fat (BRI = 364.2–365.5 × [1 – (waist circumference/2π)2/(0.5 × √height)2]), on thyroid hormone levels, hypothesizing that BRI influences thyroid hormone concentrations through a specific threshold.MethodsThis study analyzes cross-sectional data from 10,086 participants in the National Health and Nutrition Examination Survey (NHANES) obtained between 2007 and 2012. Participants underwent anthropometric measurements and thyroid hormone assessments. We employed multiple linear and piecewise regressions to examine associations between BRI and the following thyroid hormones: free triiodothyronine (FT3), total triiodothyronine (TT3), free thyroxine (FT4), total thyroxine (TT4), and thyroid-stimulating hormone (TSH). We assessed nonlinearity and threshold effects and reported 95% confidence intervals and p-values.ResultsThe median age of participants was 43 years, with a BRI ranging from 0.77 to 19.33. After adjustments, a positive correlation was found between BRI and both TT3 (β = 0.95, 95% CI: 0.68–1.23) and TT4 (β = 0.06, 95% CI: 0.04–0.08). In contrast, a negative correlation was observed between BRI and FT4 (β = –0.03, 95% CI: –0.04 to –0.01). Threshold analysis revealed that when BRI was below 7.21, FT3 and TT3 increased with rising BRI, but this effect weakened or reversed beyond this threshold.ConclusionIn the American population, BRI is associated with non-linear relationships and threshold effects regarding thyroid hormone levels. Positive correlations exist between BRI and TT3/TT4, while a negative correlation is noted with FT4. Moreover, the dynamic threshold effect of BRI on FT3 and TSH indicates that visceral fat distribution characteristics should be considered when evaluating thyroid hormones. |
| format | Article |
| id | doaj-art-3d657a8800544a50b3d8c41708267ba2 |
| institution | DOAJ |
| issn | 2296-861X |
| language | English |
| publishDate | 2025-07-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Nutrition |
| spelling | doaj-art-3d657a8800544a50b3d8c41708267ba22025-08-20T03:14:58ZengFrontiers Media S.A.Frontiers in Nutrition2296-861X2025-07-011210.3389/fnut.2025.15390221539022Body roundness index, thyroid hormones, and threshold effects in US adults: a cross-sectional study from NHANESSijia Yang0Kun Liao1Lu Zhou2Shengbo Zhang3Jianchao Wu4Department of Thyroid Diagnosis and Treatment Center, Zhuhai People’s Hospital (The Affiliated Hospital of Beijing Institute of Technology, Zhuhai Clinical Medical College of Jinan University, Zhuhai, ChinaDepartment of Breast Surgery Ward, Zhuhai People’s Hospital (The Affiliated Hospital of Beijing Institute of Technology, Zhuhai Clinical Medical College of Jinan University, Zhuhai, ChinaZhuhai Clinical Medical College of Jinan University (Zhuhai People’s Hospital, The Affiliated Hospital of Beijing Institute of Technology), Guangzhou, ChinaZhuhai Clinical Medical College of Jinan University (Zhuhai People’s Hospital, The Affiliated Hospital of Beijing Institute of Technology), Guangzhou, ChinaDepartment of Thyroid Diagnosis and Treatment Center, Zhuhai People’s Hospital (The Affiliated Hospital of Beijing Institute of Technology, Zhuhai Clinical Medical College of Jinan University, Zhuhai, ChinaBackgroundThe correlation between visceral adipose tissue and thyroid hormones is debated, and the conventional body mass index (BMI) is insufficient for differentiating fat distribution patterns. This study investigates the nonlinear relationship and threshold effects of the Body Roundness Index (BRI), a geometric metric of visceral fat (BRI = 364.2–365.5 × [1 – (waist circumference/2π)2/(0.5 × √height)2]), on thyroid hormone levels, hypothesizing that BRI influences thyroid hormone concentrations through a specific threshold.MethodsThis study analyzes cross-sectional data from 10,086 participants in the National Health and Nutrition Examination Survey (NHANES) obtained between 2007 and 2012. Participants underwent anthropometric measurements and thyroid hormone assessments. We employed multiple linear and piecewise regressions to examine associations between BRI and the following thyroid hormones: free triiodothyronine (FT3), total triiodothyronine (TT3), free thyroxine (FT4), total thyroxine (TT4), and thyroid-stimulating hormone (TSH). We assessed nonlinearity and threshold effects and reported 95% confidence intervals and p-values.ResultsThe median age of participants was 43 years, with a BRI ranging from 0.77 to 19.33. After adjustments, a positive correlation was found between BRI and both TT3 (β = 0.95, 95% CI: 0.68–1.23) and TT4 (β = 0.06, 95% CI: 0.04–0.08). In contrast, a negative correlation was observed between BRI and FT4 (β = –0.03, 95% CI: –0.04 to –0.01). Threshold analysis revealed that when BRI was below 7.21, FT3 and TT3 increased with rising BRI, but this effect weakened or reversed beyond this threshold.ConclusionIn the American population, BRI is associated with non-linear relationships and threshold effects regarding thyroid hormone levels. Positive correlations exist between BRI and TT3/TT4, while a negative correlation is noted with FT4. Moreover, the dynamic threshold effect of BRI on FT3 and TSH indicates that visceral fat distribution characteristics should be considered when evaluating thyroid hormones.https://www.frontiersin.org/articles/10.3389/fnut.2025.1539022/fullcross-sectional studybody roundness indexobesityNHANESthyroid hormones |
| spellingShingle | Sijia Yang Kun Liao Lu Zhou Shengbo Zhang Jianchao Wu Body roundness index, thyroid hormones, and threshold effects in US adults: a cross-sectional study from NHANES Frontiers in Nutrition cross-sectional study body roundness index obesity NHANES thyroid hormones |
| title | Body roundness index, thyroid hormones, and threshold effects in US adults: a cross-sectional study from NHANES |
| title_full | Body roundness index, thyroid hormones, and threshold effects in US adults: a cross-sectional study from NHANES |
| title_fullStr | Body roundness index, thyroid hormones, and threshold effects in US adults: a cross-sectional study from NHANES |
| title_full_unstemmed | Body roundness index, thyroid hormones, and threshold effects in US adults: a cross-sectional study from NHANES |
| title_short | Body roundness index, thyroid hormones, and threshold effects in US adults: a cross-sectional study from NHANES |
| title_sort | body roundness index thyroid hormones and threshold effects in us adults a cross sectional study from nhanes |
| topic | cross-sectional study body roundness index obesity NHANES thyroid hormones |
| url | https://www.frontiersin.org/articles/10.3389/fnut.2025.1539022/full |
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