Have you ever felt like something’s just… off?

You’re nourishing yourself, moving your body, staying hydrated, even working on getting more sleep – but your energy still flatlines by mid-afternoon – or you’re tired from the minute you wake up. You feel like you’re dragging yourself through the day. Your mind feels foggy, your motivation has dipped and you're left wondering: What am I missing?

It’s one of the most common conversations I’ve had in clinical practice over the past 25 years. A woman sitting across from me, frustrated and fatigued, often chalking it all up to stress or "getting older" – when, in reality, her body is simply crying out for a very specific kind of support. In many of those cases, the missing link was iron.

Now, I know iron isn’t the most glamorous nutrient – it’s not new or trendy – but its role in the body is nothing short of profound. And one of the most overlooked ways it impacts your wellbeing is through your metabolism.

We tend to think of metabolism in terms of how easily we gain or lose weight. But metabolism is so much more than that. It’s your body’s entire energy-making system – every breath you take, every heartbeat, every thought – all depend on the chemical processes we collectively call metabolism. And those processes depend heavily on your iron status.

Iron: The unsung metabolic hero

Iron is essential for the creation of haemoglobin, the protein in your red blood cells that carries oxygen from your lungs to every cell in your body. Without enough iron, you can’t deliver adequate oxygen to your tissues. Without oxygen, your cells can’t efficiently produce energy. That’s where metabolism comes in. Your metabolism isn’t just the fuel (measured as calories or kilojoules) you use. It’s the sum of all the chemical reactions in your body that keep you alive and functioning – from digesting your food and circulating blood, to regulating your hormones and synthesising new cells.

When iron is low, oxygen supply can be compromised and your entire metabolic engine has to downshift. This can leave you feeling tired, sluggish, foggy and unmotivated. It can also affect the function of key metabolic powerhouses – particularly your thyroid gland.

Iron and thyroid hormone production

Your thyroid governs the pace of your metabolism, like a master dimmer switch. But for your thyroid to do its job, it needs a steady supply of iron. Iron is a cofactor in the production of thyroid hormones and when levels are suboptimal, hormone production can slow. That’s why low iron can mimic the symptoms of an underactive thyroid: body fat gains, cold hands and feet, dry skin, fatigue, hair thinning and low mood. On top of that, you also need iron to convert inactive thyroid hormone (T4) into active thyroid hormone (T3), the latter being the one that drives the pace. The trouble is, all of this often gets missed. You might be told your thyroid is “normal” or that your iron levels are “low but not low enough to treat”. But that doesn’t mean your body isn’t struggling.

Could this be you?

So many women tell me they’ve tried everything – eating well, exercising, managing stress – and yet they still feel flat, foggy, or fatigued. And so often, when I test their iron levels properly, we discover they’ve been running on empty, or close enough to it. In fact, even a “normal” iron result may not mean you have optimal iron. There’s a difference – and it matters.

In my clinical experience, I begin treating individuals with ferritin levels below 50 µg/L, as they are often already feeling the effects of suboptimal iron, or they’re heading toward deficiency if action isn’t taken.

What to do next

If any of this sounds familiar, it might be time to take a closer look at your iron status. Ask your healthcare provider for a full iron panel (called iron studies) – not just serum iron or haemoglobin. The iron studies group of tests includes serum iron, ferritin (your iron stores), transferrin saturation and transferrin or total iron-binding capacity. And if your iron levels are low or borderline (lower end of the normal range), don’t just settle for “let’s watch it”. Addressing it now can support your metabolism, mood, hormones and energy in ways you may not have realised were connected.