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Should You Take T3 for Weight Loss? What the FDA Warns

By Norma Ector · · Updated

Contents

T3 (triiodothyronine) is a thyroid hormone your body makes naturally. Its prescription form, liothyronine (brand name Cytomel), treats an underactive thyroid.

T3 is not a weight-loss drug. Its FDA label carries a boxed warning against using thyroid hormone to treat obesity in people whose thyroid works normally.

In this article, we will cover what T3 is, why it is a poor and risky choice for weight loss, how doctors actually prescribe it, side effects, and safer alternatives.

Reasons You Should Take T3

The only good reason to take T3 is a thyroid condition diagnosed and treated by your doctor. Liothyronine is prescribed for hypothyroidism, for some types of enlarged thyroid, and for certain thyroid tests.

T3 is often promoted online for weight loss because thyroid hormone sets how fast your body uses energy. That logic does not hold up in people with a normal thyroid.

The MedlinePlus liothyronine drug information states that thyroid hormone does not help with weight loss in people with normal thyroid function. Larger doses can cause serious or life-threatening toxicity.

That risk rises when T3 is combined with stimulants such as amphetamines, which are also sometimes sold for appetite control or weight loss.

How to take t3

Liothyronine comes as a prescription tablet. Take it exactly as your doctor prescribes and do not change the dose on your own.

Your doctor will check your thyroid levels with blood tests and adjust the dose over time. Never take T3 bought online without a prescription or "thyroid boosters" that may contain hidden hormone.

Benefits of T3

how to take t3 for weight loss

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For people with hypothyroidism, T3 replaces missing thyroid hormone. That can relieve symptoms such as fatigue, feeling cold and some of the weight gain linked to an underactive thyroid.

For people with normal thyroid levels, there is no proven weight loss benefit. Any weight that does come off at high doses can include muscle, and it comes with real risks to the heart.

If you suspect a thyroid problem is behind weight gain, ask your doctor for a thyroid blood test before looking for weight loss shortcuts.

Potential Side Effects

Too much thyroid hormone can cause a fast or irregular heartbeat, chest pain, nervousness, excessive sweating, heat sensitivity and temporary hair loss.

Call your doctor right away if you have chest pain or a racing or irregular heartbeat. Long-term overuse of thyroid hormone can also strain the heart and weaken bones.

Dosage Guidelines

There is no safe "weight-loss dose" of T3. The dose for a thyroid condition is set by your doctor based on your diagnosis, age, heart health and blood tests.

Do not follow dosing advice from forums, bodybuilding sites or sellers. Taking more than prescribed does not speed up healthy weight loss; it raises the risk of toxicity.

When to Take T3

Liothyronine is usually taken once a day. Take it at the same time each day, following your prescription label, to help keep your blood levels steady.

Foods to Avoid

t3 for weight loss

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No single food makes T3 unsafe. MedlinePlus advises taking the cholesterol drug cholestyramine at least 4 to 5 hours before or after liothyronine.

Calcium, iron and antacids may also interfere with thyroid hormone absorption.

Ask your pharmacist how far apart to take these from your thyroid medicine, and tell your doctor about every supplement you use.

Alternatives to Taking T3

If your goal is weight loss, safer evidence-based options include a calorie-controlled eating pattern, regular physical activity and support from a doctor or registered dietitian.

For people with obesity, doctors can prescribe FDA-approved weight-loss medications, which require medical supervision. Bariatric surgery is another option for people who qualify.

Conclusion

T3 is a prescription hormone for thyroid disease, not a tool for weight loss. The FDA label warns that it does not help people with normal thyroid function lose weight and that high doses can be dangerous.

If you are struggling with your weight, talk with your doctor about a thyroid test and about approved treatment options.

FAQs:

What is T3?

T3 (triiodothyronine) is a thyroid hormone your body makes. Its prescription form, liothyronine, treats an underactive thyroid (hypothyroidism). It is not approved for weight loss.

Does taking T3 help with weight loss?

Not in people with normal thyroid function. The FDA boxed warning says thyroid hormones should not be used to treat obesity or for weight loss, because normal doses do not reduce weight and larger doses can cause serious or life-threatening toxicity.

What are the potential side effects of taking T3?

Too much thyroid hormone can cause a fast or irregular heartbeat, chest pain, nervousness, sweating, heat intolerance and trouble sleeping. Call a doctor right away for chest pain or a racing or irregular heartbeat.

Are there foods or supplements to avoid when taking T3?

The cholesterol drug cholestyramine should be taken 4 to 5 hours apart from liothyronine, and calcium, iron and antacids may also interfere with absorption.

Ask your pharmacist how to space them.

What are some alternatives to taking T3 for weight loss?

A calorie-controlled diet, regular activity, FDA-approved weight-loss medications prescribed by a doctor, and bariatric surgery for people who qualify are the evidence-based options.

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