Levothyroxine should not be used to treat obesity or for weight loss. This can cause dangerous side effects, especially if you combine levothyroxine with another drug that causes weight loss, such as dextroamphetamine or methamphetamine.
When you start taking thyroid medication like levothyroxine, don't expect instant weight loss. The first barrier is getting the right dose of thyroid medication. Once you have reached your ideal dose, you may notice some weight loss after around three to six months of continuous use.
While undertreatment with levothyroxine can lead to weight gain, overtreatment can result in weight loss as well as adverse effects including bone and muscle loss and heart problems, especially arrhythmias. Once the excess hormone is stopped (that is, the dose is adjusted downward), the weight is typically regained.
Generally, people begin to notice weight loss about three to six months after hitting a therapeutic dose of their medication. People lose about five to ten pounds on thyroid medication or less than 10% of their body weight.
Adults usually start with a dose between 50 micrograms and 100 micrograms taken once a day. This may be increased gradually over a few weeks to between 100 micrograms and 200 micrograms taken once a day. Some people, such as over-50s or people with heart disease, may start on a lower dose.
When you start levothyroxine you won't feel better the next day. You may not feel better in two weeks. But symptoms should start disappearing within a month. After six weeks of treatment, you should be almost completely free of symptoms, assuming you're at the right medication level.
Levothyroxine is used to treat hypothyroidism, a condition where the thyroid gland does not produce enough thyroid hormone. Levothyroxine is also used to help decrease the size of enlarged thyroid glands (also called a goiter) and to treat thyroid cancer. This medicine is available only with your doctor's prescription.
The most commonly prescribed thyroid hormone is called levothyroxine (Synthroid®), but there are others available. Thyroid hormones increase the body's metabolism which may cause weight loss.
Common side effects of levothyroxine include heat intolerance, a fast heart rate, and diarrhea. More serious levothyroxine side effects are also possible. If you experience side effects like tremors or mood changes, talk to your healthcare provider as soon as you can.
Once your thyroid levels are normal again, this medication should have no effect on your weight. Levothyroxine should not be used to treat obesity or for weight loss.
Current guidelines recommend a levothyroxine dosage of 1.6 mcg per kg per day based on ideal body weight or lean body mass instead of actual body weight. Ideal body weight can be calculated as the weight for height that would generate a body mass index of 24 to 25 kg per m2.
As with most medications, if you've gained or lost weight, you may need to adjust the dose of your thyroid medication. Your provider will calculate how much to add or take away based on your weight change and monitor how well you do with the new dosage.
Where daily hormone replacements tablets, such as levothyroxine, are prescribed for an underactive thyroid, symptoms including fatigue should gradually begin to disappear. Similarly, patients receiving anti-thyroid drugs for an overactive thyroid should begin to see an improvement in their energy levels.
Hypothyroidism has traditionally been associated with obesity, whereas hyperthyroidism has been linked to being underweight. However, very few studies have assessed these associations.
Levothyroxine is absorbed in the small intestine and is 70%-80% bioavailable in the euthyroid individual. Peak absorption is achieved at approximately 2 hours after oral ingestion but can be delayed to 3-4 hours if it is ingested simultaneously with interfering medications, supplements, or some foods/drinks.
Levothyroxine is used to treat an underactive thyroid (hypothyroidism). It replaces or provides more thyroid hormone, which is normally produced by the thyroid gland. Low thyroid hormone levels can occur naturally or when the thyroid gland is injured by radiation/medications or removed by surgery.
Pushing the thyroid hormone dose to cause thyroid hormone levels to be elevated is unlikely to significantly change weight and may result in other metabolic problems.
Hypothyroidism slows down your metabolism, making it more difficult to lose extra pounds and maintain a healthy body weight.
Extreme tiredness is a commonly reported side effect of Levothyroxine. Many people begin treatment but feel no better after starting medication, which may be because they are experiencing this effect. You feel more tired while taking Levothyroxine because the hormones in your body have been effectively reduced.
You should start to feel better a few days after you begin taking medicine. But it may take a few months for your thyroid hormone levels to get back to normal. If your levels get better, but you still have symptoms like fatigue and weight gain, your doctor may need to change your treatment.
Levothyroxine is generally well-tolerated, but it still has the potential to cause side effects. Heat intolerance, sweating, and diarrhea have been reported, especially when you're first starting the medication or changing doses.