Thyroid conditions and weight gain - Q & A

This fact sheet lists a range of questions and answers on thyroid conditions and weight gain. The questions were posted by visitors to the Better Health Channel and answered by a panel of experts, which includes general practitioners, nutritionists, physical activity professionals and other health and medical specialists.

Q. I've had an underactive thyroid (Hashimoto's) for two years and I feel terrible. My weight sticks around 84kg and won't budge. My doctor has put me on iron tablets (as my iron levels were low) and said it would help me get the energy to do more exercise. Three months later it hasn't and I still feel tired and I am putting on weight. All this is really getting me down as I am used to being a lot slimmer than I am now, and having much more energy (and patience). The doctors just say to exercise more and eat less. I even had one doctor shove a diet company’s pamphlet in my face. Please help me as I am getting more and more down.
The question you ask is one of the most common we hear at Thyroid Australia: ‘I try very hard to eat properly, and to exercise, and yet I cannot lose weight’. I have a couple of theories as to why hypothyroid patients struggle to lose weight, some of which relate to the length of time it took to be diagnosed.

I know in my case it was nearly a decade before I was diagnosed and, in that time (when my free T4 and free T3 levels were low), I often turned to high kilojoule foods to get the extra energy I lacked. I also struggled to get motivated to exercise, because my muscles ached so that physical activity was uncomfortable.

Try to get the hormone levels ‘right’
I don't know what it’s like for other hypothyroid patients, but I would like to suggest that these may be common problems. Such bad habits are difficult to break, especially when your thyroid hormone levels are not in the right range for your own body. I also know that I managed to lose weight quite easily when my free T4 levels were in the upper part of the reference range. I managed to control my desire for sweet and fatty foods and set up and stuck to a decent exercise program.

Most hypothyroid patients will find it difficult to lose weight when their free T4 and free T3 levels are towards the lower end of the range. Metabolising food properly and having enough energy is difficult when you have hypothyroid symptoms. I feel there are some questions that you need to think about:

• What are your thyroid hormone levels, and where do they fall in the laboratory’s reference ranges?
• What is your weight?
• What other medications (both prescribed and over-the-counter) do you take?
• Do you have any other medical condition that could be affecting you?
• Do you take your thyroid hormone by itself on an empty stomach, or do you take it in conjunction with other medications or with food?

Current research and our own experience at Thyroid Australia suggest that thyroid patients tend to feel better when their thyroid stimulating hormone (TSH) is at the lower end of the reference range and their free T4 (thyroxine) level is at the higher end of the reference range. You need to know what your laboratory's reference range is, and every laboratory has different reference ranges. We recommend that all thyroid patients obtain photocopies of their thyroid function test results from their doctors.

Some professionals recommend that, generally speaking, patients need a thyroxine dose (in micrograms) of around twice their body weight for a full thyroid hormone replacement dose. For example, if a patient weighs 75kg, they need to take around 150mcg of thyroxine. Men, children, and pregnant and lactating women tend to need more, and older people tend to need less. It is also believed that the ‘lean body weight’ (muscle tissue) has an effect on the dosage of thyroxine. This needs to be discussed with your doctor in order to get the dosage right. Don’t, however, increase your dose without first checking with your doctor that it is safe for you to do so.

Don’t take thyroxine and iron at the same time
There is some evidence to suggest that substances such as iron and calcium (and others) can affect the absorption of thyroid hormone. You need to make sure that you do not take your thyroxine tablets with your iron tablets, as the iron tablets can affect the absorption of your thyroxine. Take them a couple of hours apart and see if this has any effect on your thyroid hormone levels and how you are feeling.
We have literature that suggests that thyroxine is best absorbed if taken on an empty stomach about half an hour or so before eating.

Make sure you don’t have any other illnesses
It is easy to blame a thyroid problem for anything that is going wrong (I know, I have done it), but sometimes there are other conditions (possibly undiagnosed) that may affect how we feel. For example, is your anaemia (lack of iron) caused by ordinary anaemia, or do you suffer from pernicious anaemia?

Pernicious anaemia is caused by a lack of intrinsic factor, a substance needed to absorb vitamin B12 from the gastrointestinal tract. Pernicious anaemia is more common among those who suffer from autoimmune conditions such as Hashimoto's thyroiditis. It is treated by regular injections of vitamin B12. I suggest that you find out what sort of anaemia you are suffering from and ensure that you are receiving the appropriate treatment.

Talk to your doctor
My suggestion is that you ask your doctor for another thyroid function test, and ask for your thyroid stimulating hormone (TSH), free T4 and free T3 levels to be checked.

Get a photocopy of your test result and see whether your TSH level is near the bottom of the reference range and whether your T4 and T3 levels are towards the upper end of their reference ranges.

If they are not, ask your doctor whether you can increase your dose until your T4 and T3 levels are closer to the upper end of their ranges, and then see how you feel and whether you have more success at losing weight. But do bear in mind that, once you have lost weight, your dose of thyroxine might have to be lowered as your body’s requirements will be lessened.

Where to get help

• Your doctor
• Endocrinologist
• Thyroid Australia Tel. (03) 9888 2588

You might also be interested in:

• Goitre.
  
• Thyroid conditions - Hashimoto's disease.
  
• Thyroid disorders - hyperthyroidism.
  
• Thyroid disorders - hypothyroidism.
  
• Thyroid gland explained.
  
• Thyroid issues - the parathyroid glands.
  

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Thyroid Australia

Last updated: September 2008

The information published here was accurate at the time of publication and is not intended to take the place of medical advice. Please seek advice from a qualified healthcare professional.

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