You're eating well. You're moving your body. You're doing everything you're supposed to do. Yet the weight won't budge. If that sounds familiar, I want you to know something important: it's not a willpower problem. It might be your thyroid.
I know this one personally. A few years into perimenopause, I noticed weight creeping on despite my best efforts. My energy was low, my mood was off, and I just didn't feel like myself. I put it all down to "the change" Honestly, that's what most women do. Thyroid issues run in my family history, so when I finally investigated my thyroid, everything clicked into place. Suddenly the symptoms that had seemed so random made complete sense.
Why the thyroid matters so much for weight
Your thyroid is a small butterfly-shaped gland in your neck and it has an enormous job: It regulates your metabolism. Think of it like the thermostat in your home. When it's working well, everything runs at the right temperature. When it's sluggish (a condition called hypothyroidism), your metabolism slows down, and your body starts holding onto weight even when you're doing all the right things.
The tricky part? Even a mild thyroid issue - one that might be sitting just outside the "abnormal" range on a standard blood test - can have a very real impact on how you feel and how your body responds to food and exercise. Many women are told their results are "normal" and sent on their way, still feeling terrible and wondering what's wrong with them. Nothing is wrong with you. You just haven't had the full picture yet. This is why I’m so passionate about full panel Thyroid hormone testing . This allows us to get a complete picture.
The perimenopause overlap that trips women up
Here's where it gets complicated. Thyroid symptoms and perimenopause symptoms look almost identical. Fatigue, weight gain, brain fog, mood changes, disrupted sleep, feeling cold - they're on both lists. And irregular periods, which most women understandably chalk up to perimenopause, can also be a sign of thyroid dysfunction. This is exactly why thyroid issues get missed so often in women in their 40s and 50s. We assume it's hormones. Sometimes it is. But sometimes, it's both.
What makes this even more layered is that perimenopause can directly affect thyroid function. Fluctuating oestrogen levels can increase a protein called thyroid-binding globulin, which means less thyroid hormone is actually available for your body to use, even when your levels look "normal" on paper.
And the relationship between progesterone and the thyroid is a true chicken-and-egg scenario: we need adequate thyroid hormone for the ovaries to produce progesterone, yet as progesterone declines, it hinders the production and functioning of the thyroid itself - each one making the other's job harder at exactly the wrong time. This hormonal interplay is why so many women in perimenopause develop thyroid issues during this life stage. This is why looking at both together, rather than in isolation, is so important.
What you can do right now
Ask for a full thyroid panel. TSH alone doesn't tell the whole story. Ask your GP to also test Free T3, Free T4, and thyroid antibodies. This gives a much clearer picture of how your thyroid is actually functioning day to day. GPs do the best they can, if they do not believe a full panel is warranted, you can order these tests privately through a Naturopath (Ahem, like me - wink wink). A consultation would be required to process this request.
Look at the full picture. Thyroid dysfunction rarely exists in isolation. Nutrient deficiencies (especially iodine, selenium, zinc, and iron), chronic stress, and gut health all influence how well your thyroid works. Addressing these alongside any medical treatment can make a meaningful difference.
Don't dismiss "subclinical" results. If your results come back borderline, don't let them be brushed aside. Subclinical hypothyroidism is real, and its impact on weight, energy, and mood is real too. You deserve to be heard and you deserve a practitioner who will dig deeper with you.
Your symptoms are telling you something
Stubborn weight gain in perimenopause isn't something you just have to accept. It's a signal worth investigating, and your thyroid is one of the first places to look. When you understand what's actually driving the problem, you can finally start addressing it in a way that works.
If you're not sure where to start, my free Metabolism Detective Quiz is designed to help you identify what might actually be driving your weight gain and whether it's your thyroid, your hormones, insulin resistance, or excess cortisol maybe contributing. Click the ‘Metabolism Detecive’ tab on the homescreen for your free download. Try it as a starting point to work out if your thyroid maybe contributing to how you’re currently feeling.
