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What’s The Science Behind Ashwagandha For Thyroid And Ashwagandha For Weight Loss?

Ashwagandha is mainly known as an anxiolytic, but it has been shown to have other, sometimes physical effects. There is compelling evidence that ashwagandha raises thyroid hormone levels to restore thyroid functioning, which boosts your metabolism to aid in weight loss. 

Ashwagandha And Thyroid Issues

Thyroid issues either present as hypothyroidism where thyroid hormone levels are low, or as hyperthyroidism ー the result of an overactive thyroid. Ashwagandha is one possibility for treating hypothyroidism as it recovers healthy thyroid hormone levels. Though, this is not the case for hyperthyroidism.

Ashwagandha stimulates the thyroid to produce more T3 and T4 thyroid hormones ー T3 being the more active hormone. This boost in thyroid hormone increases metabolism and other vital processes. Higher levels of T3 and T4 also feedback and inhibit thyroid-stimulating hormone (TSH) until their levels reduce, by which point the cycle repeats itself. Ashwagandha therefore normalizes thyroid functioning.

All of this assumes your thyroid is at least intact and functional ー it doesn’t fix a “broken” thyroid.

Ashwagandha And Hypothyroidism

Ashwagandha boosts thyroid activity enough to treat subclinical (an early, mild form) hypothyroidism. One study found that the ashwagandha dosage for hypothyroidism is 600 mg daily of ashwagandha extract for 8 weeks.

Ashwagandha may or may not be useful for mild clinical hypothyroidism – we need more studies. You’re welcome to try it, but ashwagandha is almost certainly not strong enough for anything more severe.

By the same token, one would actually expect ashwagandha to exacerbate hyperthyroidism as it raises T3 and T4 and reduces TSH (a common presentation of hyperthyroidism). Therefore, people with hyperthyroidism should not take it.

Note that none of the above effects are permanent – it only continues as long as you take ashwagandha.

Ashwagandha And Hashimoto’s Disease

In short, ashwagandha probably won’t help unless you have early hypothyroidism. Hashimoto’s disease on the other hand destroys your thyroid altogether. Ashwagandha stimulates your thyroid to be more active, but you need a functioning thyroid gland for that. With Hashimoto’s, you have to take exogenous thyroid hormone; supplements can’t boost an organ you don’t have, or which is effectively non-functional.

Ashwagandha Thyroid Side Effects

High doses of ashwagandha may exacerbate subclinical hyperthyroidism in people with borderline overactive thyroid function. Anecdotally, a few people have reported symptoms that sound like this, but only at high doses, usually well over the 600 mg a day which we normally recommend as a maximum. 

Reported symptoms include feeling hot, anxious and having trouble sleeping (despite the normal benefits of ashwagandha being fixing anxiety and insomnia).

If you get these side effects, halve your dose. If they continue, cease ashwagandha and the side effects you’re experiencing should go away within 1-3 days.

Ashwagandha For Weight Loss

Studies sometimes find a strong association between ashwagandha and weight loss, but not consistently.

In general, studies only find weight loss in overweight people suffering from stress and anxiety. This was seen using 300mg of ashwagandha twice a day. Thus, it seems that ashwagandha probably reduces stress-eating, and perhaps also aids self-discipline by improving sleep. 

In theory, you would expect the increase in thyroid hormones to aid weight loss; this may not have been seen due to short study durations or subjects otherwise not trying to lose weight.

In studies, taking ashwagandha for weight loss only amounted to 2-4 pounds over 8 weeks ー it wasn’t a lot, but that’s decent for a supplement that also improves mental health, energy level and overall quality of life.  

Interestingly, caloric deficits normally decrease thyroid hormone production, i.e. people produce less T4 and T3 during weight loss diets. So ashwagandha could be used to maintain thyroid function while losing weight via other means.

Ashwagandha Dosage For Thyroid Function

Only one study has looked at thyroid function, and it used 600 mg a day of a 5% withanolide extract. This is a rather high dosage – if you take that much you should divide the dosage into two doses: 300 mg morning and evening, or even in three doses: 200 mg in the morning, afternoon and evening.

Please note that subclinical hypothyroidism is mild enough that it usually isn’t otherwise treated with thyroid hormones, just diet and lifestyle changes. This effect is mild, but if consistent, it makes ashwagandha one of the better options for boosting thyroid function. You could also try increasing your iodine intake by taking iodized salts or eating a seafood-rich diet which will help with thyroid hormone production.

You should not take ashwagandha in conjunction with thyroid hormones such as levothyroxine without talking to your doctor, however. This could have unexpected results, though most likely it would do little since exogenous thyroid hormones suppress natural thyroid function.

Ashwagandha Weight Gain

Ashwagandha is primarily an anti-anxiety supplement and should not make anyone gain weight. If anything, ashwagandha might cause a little bit of weight (mostly fat) loss through reduced stress eating, increased thyroid function, and better sleep. However, more thyroid activity can increase your appetite, so there’s an outside chance you could out-eat its thyroid benefits.

On the other hand, if you’re trying to gain weight – lifting weights, eating more – ashwagandha can help you, not so much to gain weight as to make sure most of what you gain is muscle. It increases various measures of fitness such as power output, fatigue and strength. In one study, ashwagandha helped subjects increase their bench press more than controls.

Ashwagandha and Levothyroxine/Synthroid

You might think ashwagandha would combine well with exogenous thyroid hormones such as levothyroxine. However, synthroid suppresses your natural thyroid hormone production, lowering TSH.

Ashwagandha is unlikely to overcome this suppression and thus shouldn’t do much when combined with synthroid. On the other hand, if it actually was effective, it could cause hyperthyroidism. In short, don’t combine them.

However, if you ever go off of levothyroxine or T3, ashwagandha might help you recover natural thyroid function faster, assuming you have a working (if under-active) thyroid gland.  

We can see that ashwagandha effectively resolves subclinical hypothyroidism and may in turn, reverse associated symptoms such as weight gain. However, ashwagandha loses its efficacy as hypothyroidism develops, and is also not advised for treating hyperthyroidism as it only exacerbates symptoms, especially alongside levothyroxine.

Feature image by i yunmai on Unsplash

About the author

Lucy is a UK-based freelance writer focusing on biological content, whether it may involve animal biology or health and well being. Having achieved a First Class Zoology degree at the University of Bristol, Lucy has a diverse knowledge base and enjoys writing for others. Lucy is also a medical student in London who enjoys, in her free time, weight lifting at the gym or hiking along precarious routes in the great outdoors.

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