Iron and Energy: Why So Many Women Feel Exhausted

You're tired. Bone-deep, can't-drag-yourself-out-of-bed tired. You've been told it's your schedule, your stress, maybe your sleep. Nobody's mentioned iron. But iron deficiency is the single most common micronutrient deficiency in women, and it's silently stealing your energy.

Why iron matters so much

Iron is required for haemoglobin (which carries oxygen in red blood cells) and for components of the mitochondrial electron transport chain. Iron deficiency reduces oxygen delivery and impairs cellular energy production.¹

Iron deficiency doesn't just affect energy. It affects cognition, mood, temperature regulation, and immune function. Women with low iron are more prone to depression, brain fog, cold hands and feet, and getting sick. You can have all three of these symptoms and still test "normal" on a standard blood test.

Women lose blood monthly. If you've had heavy periods, given birth, or donated blood, you've lost iron you haven't replaced. If your diet is low in bioavailable iron, you're running a deficit. Month after month. Year after year. Until you hit a wall and suddenly everything feels impossible.

How iron deficiency develops in women

Women lose blood monthly. If you're menstruating, you're losing iron every single month. If your cycle is heavy, you're losing more. If your diet is low in bioavailable iron (meat, organs, seafood) and high in processed foods, you're losing more than you're replacing. Over months, iron stores deplete. Over years, you're running on fumes.

Vegetarian and vegan women are at higher risk for iron deficiency because non-heme iron from plants is less bioavailable than heme iron from animal sources; the NIH ODS notes mixed-diet absorption around 14 to 18% versus 5 to 12% for vegetarian diets.¹

Pregnancy depletes iron dramatically. Your body needs more iron to support the pregnancy. Postpartum haemorrhage (even minor) depletes it further. Many women emerge from pregnancy with dangerously low stores and spend years replenishing.

Birth control pills can increase iron loss, especially if you have heavy periods. Stress suppresses iron absorption. Intense exercise increases iron loss through sweat. Digestive issues (IBS, coeliac, Crohn's) reduce absorption. It's not just diet. It's the whole picture.

After menopause, iron needs actually decline, which is why postmenopausal women are less likely to be iron deficient than women of reproductive age. Menopause arrives and suddenly you have energy again. This isn't coincidence. It's iron.

The hidden symptoms nobody connects

Doctors are trained to look for obvious signs: pale skin, shortness of breath, dizziness. But low iron presents in ways that get medicalised separately and never connected back to iron.

Restless legs syndrome (RLS) has been associated with low iron stores; current guidelines recommend checking serum ferritin in patients with RLS and considering iron supplementation when ferritin is below 75 ng/mL.²

Hair loss? Low iron. Nails that are thin, flat, or spoon-shaped? Low iron. Brittle nails that break constantly? Often iron (though also sometimes B12).

Brain fog that feels like early dementia? Low iron. You can't think clearly. You walk into a room and forget why. You read the same sentence five times. It feels like your brain is broken. It's not. It's underfed.

Insomnia that gets treated with sleeping pills? Paradoxically, low iron causes insomnia. Your body tries to conserve oxygen at night. You can't relax. You can't sleep. The GP prescribes a benzodiazepine. The real problem is iron.

These symptoms get treated separately, with supplements and medication that don't work, because nobody looked at iron.

What deficiency feels like

Early deficiency: fatigue that coffee can't fix, brain fog, difficulty concentrating, cold hands and feet, hair loss or brittle hair, restless legs at night.

More advanced deficiency: shortness of breath with minor exertion, pale skin, difficulty sleeping (paradoxically), irregular periods or very heavy periods, intense cravings for non-food items (ice, dirt, starch), difficulty exercising.

Severe deficiency: you can barely get out of bed. Normal daily tasks feel impossible. You've been to every specialist. Nothing works. This is when women often get diagnosed with chronic fatigue syndrome or depression, when the actual problem is iron.

If you're exhausted and your tests come back "normal", ask specifically for iron studies. Serum iron, ferritin, TIBC, transferrin saturation. Normal complete blood count doesn't rule out iron deficiency.