Thyroid and weight: gaining or losing because of your thyroid

Unexplained weight gain or loss is a classic reason to think of the thyroid. That makes sense, because thyroid hormone helps set how fast your cells use energy (Sinha 2018). Still, the picture is more nuanced than many hope: the thyroid usually explains a few kilos, not tens.

This article belongs to the overview about your thyroid and covers the link with weight.

Does your thyroid affect your weight?

Yes, through your metabolism. With an underactive thyroid you burn a little slower and retain more fluid, which can cause mild weight gain. With an overactive thyroid you burn faster, which can cause weight loss. The effect is real but usually limited.

How much does the thyroid really explain?

Large, lasting weight changes rarely come from the thyroid alone.

Gaining with an underactive thyroid

If you gain weight without a change in diet, plus tiredness and feeling cold, an underactive thyroid may play a role. Read on about the underactive thyroid.

Losing with an overactive thyroid

If you lose weight unintentionally while eating normally, with palpitations, that fits an overactive thyroid. See also your TSH level.

What can you do?

A blood test brings clarity on whether your thyroid plays a role. You can have a thyroid function test at Vitalcheck without a referral, and discuss an abnormal value with your GP.

References

• Sinha RA, et al. Direct effects of thyroid hormones on hepatic lipid metabolism. Nat Rev Endocrinol. 2018. PMID: 29472712.
• Chaker L, et al. Hypothyroidism. Lancet. 2017. PMID: 28336049.
• Thuisarts.nl. About your thyroid.

Every blood test result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.