Jump to: What is hypothyroidism? | What is Mounjaro? | Why take Mounjaro if you have hypothyroidism? | Take home message
You can take Mounjaro (tirzepatide) if you have an underactive thyroid (hypothyroidism) and your BMI is over 27. There are no known interactions between Mounjaro and thyroid medications like levothyroxine.
However, hypothyroidism can affect your metabolism and make weight loss more challenging. Your thyroid levels must be well-controlled with medication before starting Mounjaro.
No studies have yet investigated the impact of Mounjaro on weight loss for people living with hypothyroidism, so it’s unclear how well Mounjaro will work in people living with hypothyroidism.
Theoretically, Mounjaro could counteract the effects of an underactive thyroid by reducing appetite and helping people eat less. However, this is speculative and has not yet been demonstrated in the literature.
Research has shown that tirzepatide can lower circulating thyroid-stimulating hormone (TSH) levels. TSH is crucial in maintaining healthy thyroid function.
Still, it’s unclear whether this reduction in TSH observed on GLP-1 medications like Mounjaro will prevent weight loss.
If you take Mounjaro with hypothyroidism, it’s recommended that you continue your prescribed thyroid medication exactly as directed. Your healthcare team should monitor your thyroid levels regularly.
Some people with hypothyroidism may need adjustments to their thyroid medication as they lose weight. This is normal and should be managed by your healthcare provider.
On Second Nature’s Mounjaro weight-loss programme, the clinical team monitors your progress and response to medication.
All Second Nature members have access to a nutritionist or dietitian five days a week for habit change and diet support.
What is hypothyroidism (underactive thyroid)?
Hypothyroidism occurs when your thyroid gland doesn’t produce enough thyroid hormones (T3 and T4). These hormones are crucial in regulating your metabolism, energy levels, and weight.
The most common cause of hypothyroidism is Hashimoto’s disease, an auto-immune disorder where the immune system attacks the thyroid gland.
Chronic inflammation and insufficient iodine intake can also cause hypothyroidism. Common symptoms include fatigue, weight gain, cold sensitivity, dry skin, and depression.
Research shows that people with hypothyroidism often have a lower metabolic rate (they burn fewer calories each day), which can make losing weight more difficult even with diet and exercise.
The condition is usually treated with levothyroxine, which replaces the missing thyroid hormone. When properly treated, most symptoms improve, including the ability to manage weight more effectively.
However, even with treatment, some people struggle to maintain a healthy weight due to the complex relationship between thyroid function and metabolism.
What is Mounjaro?
Mounjaro is a dual-action weight-loss injection. It supports weight loss by mimicking two hormones, GLP-1 and GIP, that communicate with the brain’s appetite control centre, the hypothalamus, to lower hunger and food-seeking behaviour.
By lowering hunger and our desire to eat, Mounjaro helps us eat fewer calories to achieve a calorie deficit.
A calorie deficit occurs when we consume fewer calories than our body needs to fuel its essential functions, such as digestion, blood flow, and brain function.
By creating a calorie deficit, our bodies will ‘burn’ the excess fat stored for energy, and we’ll lose weight.
Mounjaro also slows down the rate at which we digest food so that our stomach and gut send signals to the brain to signal the feeling of fullness.
So, Mounjaro supports weight loss by making us feel less hungry through two mechanisms:
1. Communicating with the brain’s appetite control centre
2. Slowing the rate that food is digested
Randomised controlled trials have shown that Mounjaro leads to an average weight loss of around 26% after one year.
Why take Mounjaro if you have hypothyroidism?
GLP-1 medications like Mounjaro could be beneficial for people with hypothyroidism who struggle with their weight.
Weight loss can be incredibly challenging with hypothyroidism due to a lower metabolic rate. Mounjaro could theoretically help people overcome this.
The medication’s ability to reduce appetite and slow digestion works through different mechanisms than thyroid hormones, potentially making it a complementary treatment for weight loss.
With a lower metabolic rate, achieving a calorie deficit low enough to support weight loss can be challenging.
However, Mounjaro’s ability to communicate directly with the brain’s appetite control centre to lower hunger could induce a sustained calorie deficit to support weight loss over time.
However, research has shown that Mounjaro leads to lower thyroid stimulating hormone (TSH) levels, a hormone crucial in maintaining thyroid function.
Still, it’s unclear whether this lowering of TSH would impede weight loss in people with hypothyroidism.
People living with hypothyroidism may still find weight loss challenging on Mounjaro compared to those who don’t have the condition.
However, Mounjaro’s impact on appetite may increase the chance that people living with hypothyroidism could achieve significant weight loss.
Losing weight may help improve thyroid function and reduce the dose of thyroid medication needed. However, your healthcare team should always monitor this.
Take home message
Weight-loss injections like Mounjaro may be effective for people with hypothyroidism, particularly when thyroid levels are well-controlled with medication.
Success depends on maintaining consistent thyroid treatment while using Mounjaro. Regular monitoring of thyroid levels is essential as weight loss may affect your medication needs.
Second Nature’s medication programmes
Second Nature has two medication-supported programmes: a Wegovy weight-loss programme and a Mounjaro weight-loss programme.
Why should you choose Second Nature over other medication providers if you’ve decided to try Mounjaro or Wegovy (assuming you’re eligible)?
For peace of mind.
Second Nature has worked with the NHS for over 6 years, providing weight-loss programmes across the UK.
While our Wegovy and Mounjaro weight-loss programmes are private and not currently used by the NHS, we’ve built the programmes focusing on scientific evidence, patient safety, and data security.
We hope that our 6+ years of working with the NHS and building a track record of effective weight-loss results will give you peace of mind to give us a try.
