Can FT3 help with Sport?

FT3 (free triiodothyronine) is the active thyroid hormone that regulates basal metabolic rate and energy production. Some athletes and bodybuilders use FT3 supplements hoping to boost metabolism and enhance fat loss. However, scientific evidence for a performance-enhancing effect in healthy individuals with normal thyroid function is weak. No high-quality human studies clearly demonstrate a benefit of exogenous FT3 for athletic performance. On the contrary, uncontrolled use can suppress endogenous TSH and T4 production, potentially leading to long-term hypothyroidism. Other risks include cardiac arrhythmias, muscle wasting, and increased calorie burn without corresponding muscle gain. FT3 is classified as a doping substance in many sports. From an evidence-based perspective, FT3 is not recommended for sport; any hormonal intervention requires strict medical supervision. The provided context contains no specific studies on FT3 and sport, so this answer relies on general physiological knowledge.