Synthroid is taken orally regardless of the reason for use. For the purpose of treating hypothyroidism Synthroid doses will most commonly fall in the 100-150mcg per day range. They may be slightly higher for large individuals, but this will be determined after a period of use has passed. For the purpose of performance based fat loss, use will normally start around 50mcg per day and gradually increase as needed. With short-term use (approximately 6 weeks) the dose is increased 25mcg per day every 1-3 days until the maximum dose is reached. Doses rarely surpass 150-200mcg per day. For long-term use (approximately 12-16wks) the dose is increased -25mcg every 2-3 weeks as needed with the same 150-200mcg per day dose not being surpassed.