Hormonal
Lower Free T4 (FT4) levels within the euthyroid range are negatively associated with BMI, waist circumference, and triglycerides, and positively associated with HDL-cholesterol.
While T3 is often the focus, your Free T4 levels also matter. In this study, lower FT4 (within the normal range) was linked to lower body weight and waist size. This highlights that thyroid health is about the balance and ratio of hormones, not just hitting a 'normal' TSH number.
FT4 was negatively associated with BMI, waist circumference and triglycerides (all p-values <0.001)... The mirror image was observed for HDL-cholesterol which was negatively associated with (F) T3 and the FT3-to-FT4 ratio.
Why this rating
Large sample size, consistent with previous literature cited, but observational.
Source
Triiodothyronine and Free Thyroxine Levels are Differentially Associated with Metabolic Profile and Adiposity-Related Cardiovascular Risk Markers in Euthyroid Middle-Aged Subjects
Greet Roef et al. · Thyroid · 2013
DOI 10.1089/thy.2013.0314
More from this paper
- In euthyroid middle-aged adults, higher free T3 levels and a higher FT3-to-FT4 ratio are positively associated with unfavorable metabolic profiles (higher BMI, waist circumference, triglycerides, blood pressure, fasting glucose, and lower HDL) and increased cardiovascular risk markers (IL-6, hs-CRP, pulse wave velocity).Good
- Higher TSH levels within the normal reference range are positively associated with total cholesterol, triglycerides, and blood pressure.Good
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