The Claim
In young men undergoing prolonged physical exertion and energy deficit, serum reverse T3 (rT3) concentration increases significantly, triiodothyronine (T3) concentration decreases significantly, and there is a strong positive correlation (r = 0.6) between the magnitude of these changes, indicating a shift in peripheral thyroid hormone metabolism toward inactivation.
What the research says
Supports is higher
Support is ahead, but a single strong opposing study can change this.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
In young men who exercise intensely for long periods while consuming insufficient calories, levels of reverse T3 rise and levels of active T3 fall, with a strong statistical relationship between these changes, reflecting a metabolic shift toward thyroid hormone inactivation.
See the scientific wording
In young men undergoing prolonged physical exertion and energy deficit, serum reverse T3 (rT3) increases significantly while triiodothyronine (T3) decreases, with a strong correlation (r = 0.6) between these changes, indicating a shift in peripheral thyroid hormone metabolism toward inactivation.
When the body is under prolonged physical stress and not getting enough energy, it changes how it converts thyroid hormones. Instead of making the active form that speeds up metabolism, it makes more of an inactive form that blocks the active one. This happens because the enzymes that make the active hormone slow down, while the enzymes that make the inactive form speed up. The result is less active hormone in the blood and more inactive hormone, which lowers the body's energy use to match what's available.
What the research says
1 studyWhen young men did intense physical training without enough food, their bodies made less of the active thyroid hormone (T3) and more of an inactive version (reverse T3), which slows down metabolism to save energy. This is exactly what the claim says happens under physical stress and hunger.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.