Thyroid - How does my body make more metabolically active T3?
Your body makes T3 in two main ways. 1. Your thyroid gland produces some T3 directly, but most of what it releases is T4 (a prohormone). 2.Most T3 is made outside the thyroid by converting T4 to T3 inside tissues using enzymes called deiodinases (D1 and D2, not to be confused with Vit D). The main sites that make circulating T3 (the stuff that shows up in bloodwork) - Liver - Kidneys A different enzyme pathway (D3) converts T4 into reverse T3 (rT3), which is inactive and competes with T3 signaling. So if you “feel hypothyroid” with normal labs, it can be a conversion and signaling problem, not just a “thyroid gland problem.” What increases T3 (and supports more T4 to T3 conversion)? 1. Stop the biggest T3-lowering triggers These are the most common reasons the body lowers T3 (often as a protective adaptation). - Severe calorie restriction / starvation-like dieting tends to lower T3 and can raise rT3. - Very low carbohydrate intake can lower T3 in humans; studies show T3 drops when carbs are sufficiently low, and rT3 can rise more with very low carb intake. - High stress, - poor sleep, - illness, - inflammation commonly shift conversion away from T3 and toward conservation patterns (including more rT3). 2. Hit the key “conversion nutrients” (food first) The deiodinase enzymes and thyroid signaling depend heavily on nutrient status. - Selenium supports deiodinase activity involved in T4 to T3 conversion. Food- seafood, eggs; Brazil nuts in small amounts (easy to overdo, sometimes salty, rancid, high fat). - Iron status matters for thyroid physiology and enzyme function; low ferritin can mimic hypothyroid symptoms and impair performance. Food - red meat, lentils/beans; pair plant iron with vitamin C foods. - Zinc supports thyroid hormone metabolism (often low in restricted diets).Food - meat, shellfish, pumpkin seeds. If you supplement, it’s smartest to do it based on labs (especially iron). Do NOT self medicate.