Hyperthyroidism and Basal Metabolic Rate (BMR): The Connection

True. Hyperthyroidism—excess thyroid hormone production—directly elevates basal metabolic rate (BMR).

Mechanism

Thyroid hormones (T3/T4) regulate cellular metabolism. Excess hormone increases:

• Oxygen consumption and heat production
• Lipolysis and gluconeogenesis
• Cardiac output and heart rate
• Sympathetic nervous system sensitivity

Clinical Manifestations

• Weight loss despite increased appetite
• Tachycardia, palpitations, arrhythmias
• Heat intolerance, excessive sweating
• Tremor, anxiety, insomnia
• Diarrhea, muscle weakness

Diagnosis

Low/suppressed TSH, elevated free T4 and/or T3. Radioactive iodine uptake and antibodies (TSI, TPO) determine etiology (Graves', toxic nodules, thyroiditis).

Treatment normalizes thyroid levels, thereby restoring BMR.