Stress is a word that seems all too common in today’s society. It can wreak havoc on your overall health and affect your thyroid too. Stress slows your body’s metabolism by affecting the thyroid. This is another way that stress and weight gain are linked. Stessr can cause T4 to shunt towards Reverse T3 (rT3). RT3 is antagonist to T3, so will bind to T3 receptors blocking the action of T3.