Thyroid Hormones (T3/T4) Guide

Thyroid hormones, primarily T3 (triiodothyronine) and T4 (thyroxine), are the master regulators of the body's metabolic rate. Produced by the thyroid gland, they dictate how quickly your cells use energy, impacting everything from body temperature and heart rate to weight management. As we age, thyroid function can decline, leading to subclinical hypothyroidism, a condition associated with a slower metabolism, weight gain, fatigue, and cognitive fog—all markers of an increased biological age. Ensuring the thyroid is functioning optimally, and treating any deficiencies under medical supervision, is a foundational step in maintaining a youthful metabolism and a lower biological age.