You feel anxious for no reason. As if your life wasn’t stressful enough, iron deficiency can trick you into feeling even more anxious. A lack of oxygen revs up your body’s sympathetic nervous system, which is kind of like your body’s gas pedal, Berliner says. Plus, since iron deficiency can send your heart racing, it’s easy to feel like you’re in fight-or-flight mode even when you have every reason to feel relaxed. 
You’re losing your hair. Iron deficiency, especially when it progresses into full-blown iron deficiency anemia, can cause hair loss. “It sends your body into survival mode, so your body channels oxygen to support vital functions as opposed to ones like keeping your hair intact,” explains Moritz. Don’t panic if there are a few hairs in your drain, though. Most scalps lose about 100 hairs on a good day.
You’re vegetarian or vegan. All iron is not created equal. Your body absorbs heme iron — which comes from meat, poultry and fish — two to three times more efficiently than non-heme iron from plants, says nutritionist Rania Batayneh, author of The One One One Diet. You can still get enough iron with careful meal planning. Dark leafy greens, whole grains and legumes are all rich in iron; pair them with vitamin-C-rich foods like bell peppers, berries and broccoli to boost your absorption.
You have an under-active thyroid. Iron deficiency slows your body’s thyroid function and blocks its metabolism-boosting effects, according to the National Academy of Hypothyroidism. Hypothyroidism if often missed — six in 10 people with a thyroid disease don’t know they have it, according to the American Thyroid Association — so if you notice low energy levels, weight gain or even a lower body temperature, talk to your doc. You’re pregnant. Folic acid deservedly gets a lot of pre-natal press, but babies-to-be also need iron, and they can steal mom’s stores. What’s more, many women lose a substantial amount of blood during delivery, which can lower iron counts, Moritz says. If you’re pregnant with multiples, have pregnancies close together or regularly vomit because of morning sickness, you may need to boost your iron intake. 
Your tongue looks weird. Besides sapping the color out of your tongue, low iron counts can reduce levels of myoglobin, a protein in red blood cells that supports muscle health, like the muscle that makes up the tongue, Berliner says. As a result, many people who are iron deficient complain of a sore, inflamed and strangely smooth tongue.
You have celiac or inflammatory bowel disease. Even if you get enough iron in your diet, celiac disease and inflammatory bowel diseases like Crohn’s and ulcerative colitis can lead to problems absorbing nutrients, iron included. These conditions cause inflammation in and damage to the digestive tract. If you’ve been diagnosed with any of these GI diseases, talk to you doctor about how you can increase your iron absorption.
How To Get More Iron: Iron requirements aren’t one-size-fits-all, especially for women. Women between the ages of 19 and 50 typically need 18 milligrams per day. However, if you’re pregnant, that amount bumps up to 27 milligrams. If you’re breastfeeding, you should get just 9 milligrams. Plus, how heavy your periods are could also alter your needs. Older than 50 and not menstruating? You only need 8 milligrams per day. That’s not a hard target to hit — a single serving of lentils, spinach, beef, nuts, chicken or chickpeas will all score you at least a couple milligrams.
And when it comes to iron, more isn’t necessarily better. “While most the attention is on iron deficiency, there is a concern as well for iron overload, which studies indicate can damage internal organs and may increase the risk of diabetes, heart attack and cancer, particularly in older people,” Batayneh says. Try to hit your RDA of iron, but don’t worry about going above and beyond the recommendations.