Thyroid hormones (mainly thyroxine [T₄] and triiodothyronine [T₃]) are made by the thyroid gland and play a key role in controlling the body’s metabolism — the process by which the body uses food to make energy.
Here’s how they work, explained:
1. Control the speed of metabolism
Thyroid hormones act like the body’s metabolic engine — they decide how fast or slow cells work.
- When hormone levels are high, the body burns energy faster.
- When hormone levels are low, the body burns energy slower.
2. Increase energy use
They make cells use more oxygen and produce more ATP (energy) from food.
This keeps the body warm and active.
3. Help in growth and development
In children, thyroid hormones help with brain development and normal growth.
4. Support other body systems
They help keep:
- Heart rate normal
- Digestion active
- Muscle and nerve function healthy
In short:
Thyroid hormones control how fast the body uses energy, helping regulate metabolism, growth, and body temperature.
Too little causes tiredness and weight gain (hypothyroidism), while too much causes weight loss and restlessness (hyperthyroidism).