Thyroid and weight gain

Posted by Melissa Callaghan on

Thyroid and weight gain. What's the link?

The thyroid gland is the largest gland in the endocrine system. It sits in the middle of the neck just below the Adams apple in men and it is shaped like a butterfly.

The thyroid gland produces several thyroid hormones after being asked to do so by the pituitary gland in the form of TSH (thyroid stimulating hormone). The hormones that come from the thyroid are mainly inactive (T4) and need to still be converted into their active form T3 which is needed for metabolism.

Thyroid hormones are vital for the development and metabolism of most parts of you body. When there is even a slight problem here then there will be a knock on effect throughout your body. 

Quite often what I see in my clinic is a patient who is having an issue with excess weight gain, has already had their thyroid investigated and has been told that everything is fine. This suggests that it is more to do with the production and metabolism of active T3 and that it is not being taken up by the tissues in the outer parts of the body.  This could be due to conversion from T4 to T3 which happens mainly in the liver (see the post on thyroid and fatty liver) as well as periphery conversion of inactive T4 to active T3 which happens mainly in the gut (if you have gut issues it can affect your metabolism), therefore the problem could be due to an issue with these metabolic pathways which are needed for conversion. 

What I am trying to say is that there is alot more to the story than whether you thyroid panel in your blood test came back within reference range. 

Whilst it is often the case that obesity and underactive thyroid are seen together they are not necessarily directly linked.

When overeat the body stores any excess for use later and it can be stored as fat which is called adipose tissue. It stores energy in the form of fat.



Adipose tissue becomes part of our hormone system (endocrine) as it produces a variety of hormones, cytokines, and chemokines and all of these work together to create harmony in the body. However when we gain more and more weight these cytokines create inflammation in the body leading to chronic inflammation in metabolic syndrome which plays a big role in heart disease. Adipose tissue also plays a role in thyroid hormone regulation. A hormone that is made by adipose tissue call leptin is the most obvious link between weight gain and the thyroid.

Leptin is a hormone that makes our hunger feel satisfied it also gets called the obesity hormone. The reason for this is that as the body creates more and more fat it produces more leptin and then the body can become leptin resistant. Which means that you may have a lot of leptin trying to tell the brain that you are full and satisfied but the messages just aren’t getting through and you still think that you are hungry. Leading to overeating. 

What happens is blood levels of leptin become high but the body thinks it is starving as there is no uptake of leptin to signal that brain that you are full. Not only does leptin resistance make you hungry but it also slows down metabolism as the body is shifting into starvation mode and begins to conserve energy.

The slow down of metabolism occurs due to a slow down in cellular thyroid hormone function and conversion. This is not usually detected in pathology results.

This then becomes the link between the thyroid and weight gain via leptin resistance. We see this when there is great difficulty losing weight. 

Booking an appointment either via online video chat or in our clinic can help get you on track with your thyroid health.

Who am I?

I am a Bachelor qualified Naturopath who specialises in improving metabolic processes in the body. Major areas for improvement include gut, thyroid, kidney, skin and liver health. Conditions such as hypothyroidism, fatty liver, high cholesterol, high blood pressure, type II diabetes, & irritable bowel conditions. I help my patients by giving them symptomatic relief while working on repairing the underlying causes of metabolic stress and waste accumulation. Patients experience amazing results which are seen in their blood tests with improved thyroid markers, cholesterol, and liver markers.  As well as lower blood pressure and see relief from improved gastrointestinal symptoms like the ones that mean you need to know where every single toilet is before you leave the house.

Melissa Callaghan ND, BHSc, BTeach
Clinical Naturopath


To book an appointment click here 




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