By Karen Asp

Thyroid problems can affect your weight, hair, mood, and more. Your thyroid, the butterfly-shaped gland that sits just below the Adam's apple, is a pretty powerful organ. It's responsible for many bodily functions, including keeping your heart and brain working to help your body regulate energy.

And if you're a woman, you're up to 10 times more likely than men to have issues with your thyroid. A whopping one in eight women will develop a thyroid problem at some point in their life, according to the U.S. Department of Health & Human Services.

The two most common thyroid problems are related to the production of those hormones: Hypothyroidism, or an underactive thyroid, occurs because your thyroid can’t make enough of its hormone to keep the body going as it normally does. On the flip side, an overactive thyroid–hyperthyroidism–produces too much hormone. Fortunately, “once you’re diagnosed and start treatment, many of these symptoms can be reversed,” says Rachel Bier, MD, an endocrinologist at Endocrinology Consultants in Englewood, NJ.

While not one single health issue is a sure sign of a thyroid problem, always see your doctor if you ever experience any of the following symptoms linked to hypothyroidism and hyperthyroidism.

1. You're gaining weight for no reason

Unexplained weight gain is a classic sign of hypothyroidism. “Your appetite might have increased, but it’s not like you’ve changed habits so much that you should be gaining weight,” says Rachel Pessah-Pollack, MD, an endocrinologist at ProHEALTH Care in Lake Success, NY.

Yet here’s the weird thing about the weight: It’s not like the pounds you’d gain if you were veering down a path toward obesity. Instead, “it’s a specific type of water weight so that if you push your finger on it, it doesn’t stay there,” Dr. Pessah-Pollack adds. Because your metabolism is slower, your body’s accumulating fluid. Salt may also be pushing that weight up. How much weight gain is expected? Generally about five to 10 pounds, depending on how severe your condition is, according to the American Thyroid Association.

2. You're exhausted beyond belief

Many things in life can make you tired, but the fatigue you feel with hypothyroidism goes beyond what you experience after having one or even a few nights of bad sleep.

“This is total generalized fatigue of your body, and it’s the most common symptom of this disease,” Dr. Pessah-Pollack says. Although you might be tempted to stay in bed all day on the weekends, no amount of sleep can make you feel refreshed, and even after a restful night of sleep, you’re still tired.

Here’s the kicker, though: You’re not only tired, but your movements, speech, reflexes, even your heart rate can be slower. You may also be at risk of sleep apnea, which can severely disrupt your snooze routine.

3. Your hair is changing

Don’t be surprised if your hair starts to feel or look a little different. “As a result of hypothyroidism, your hair could change texture,” Dr. Bier says. It might become dryer and more brittle, making it prone to breakage or hair loss. And while this is a rare occurrence, some people can lose the outer 1/3 of the eyebrows.

4. You're constipated

When you have hypothyroidism, all of your bodily functions slow, including the digestion and elimination of food. You get constipated either because your body’s absorbing too much water from food or your colon just isn’t contracting as it should. In both situations, your stool moves too slowly, Dr. Bier says. If the constipation is chronic, you could even suffer from issues like hemorrhoids.

5. Your periods are longer and heavier

It’s well documented that thyroid disease can affect your menstrual cycle, and even affect fertility. In the case of hypothyroidism, the thyroid hormone being in short supply means that you could have a longer cycle and heavier flows, Dr. Bier says. Your periods might even come closer together, and you might have more cramps.

6. You feel puffy or bloated

You already know that fluid retention with hypothyroidism can cause you to gain weight, but that same water weight can make your face puffy. And because your body’s also operating in slow motion, even slowing the emptying of your stomach, you could feel bloated, especially after eating.

7. You have trouble focusing

Feel like you’re battling brain fog more often than not? Difficulty concentrating or having memory problems are often reported among people who have hypothyroidism. “Although we don’t know why there’s cognitive dysfunction with hypothyroidism, some animal studies suggest there may be alterations in brain pathways that particularly affect the hippocampus, which is important for cognition,” Dr. Pessah-Pollack says.

8. You have unexplained aches and pains

Getting sore and achy after doing a new workout or engaging in strenuous activity is one thing. But the aches and pains, even tingling, you feel as a result of hypothyroidism seem to come out of nowhere, and they’re most common in your joints, Dr. Bier says.

9. You're sensitive to the cold

Feeling cold all the time? Can’t get your fingers and toes to warm up? Even if you’ve never been sensitive to the cold in the past, hypothyroidism can change that, largely because your body’s burning less energy to begin with, which means you’re producing less heat. You might even feel cold when the environment is relatively warm.

10. You're feeling down in the dumps

Depression isn’t only a stand-alone disease, it can also occur in conjunction with hypothyroidism. “There is a link between hypothyroidism and anxiety and depression, which can affect your ability to function and pay attention,” Dr. Pessah-Pollack says. A study in the Nordic Journal of Psychiatry suggests that hypothyroidism and thyroid autoimmunity is associated with depression.

11. You can't tolerate heat

Your thyroid helps regulate your body temperature, but when those thyroid hormones get out of whack, your body can’t regulate its temperature as well, and in the case of hyperthyroidism, you become intolerant of heat. “You may feel hot and sweat all the time, even if you’re in a cold environment,” Dr. Bier says.

12. You're losing weight without trying

You’re the envy of friends because you’re losing weight even though you haven’t changed anything with your workouts or diet. If anything, you may feel so hungry that you’re eating all the time so what gives?

One cause of unexplained weight loss may be that overactive thyroid. The more severe your hyperthyroidism is, the more weight you may lose, according to the American Thyroid Association. “The weight loss may range from being not noticeable to substantial, like 20 pounds,” Dr. Pekkah-Pollack says. Of course, not everybody loses weight, and some people may even gain weight, depending on how many more calories they’re eating every day.

13. You're pooping more than normal

With too much thyroid hormone in your system, your body’s processes speed up, including your digestion. “With hyperthyroidism, you have increased metabolic rate and gut motility, which results in increased frequency of bowel movements,” Dr. Pessah-Pollack says. You might even have diarrhea.

14. Your hands are trembling

With hyperthyroidism, everything in your body is in overdrive, including your nerves which are being overstimulated. As a result, you may notice some trembling in your hands, Dr. Bier says.

15. Your periods are irregular or have stopped altogether

While hypothyroidism can cause heavier and longer menstrual cycles, the opposite is true with hyperthyroidism. “Your periods may be lighter, shorter, and further apart,” Dr. Bier says. Your period might even stop altogether, which could lead to infertility issues.

16. You're not sleeping well

Americans, in general, don’t log enough sleep, but if you have hyperthyroidism, you may have so much thyroid hormone surging through your body that you’re almost too stimulated to sleep. Experiencing hot flashes and digestive issues can also disrupt sleep. “It’s often incredibly tough to fall asleep or stay asleep,” Dr. Bier says.

17. You're feeling anxious or irritable

These symptoms sound like they could describe almost any day of your week, which is why Dr. Bier admits that this is a rather vague symptom. “Because your body is in such an overactive state, you could have mood changes,” she says. That anxiety and irritability may be exacerbated if you’re also not sleeping well.

18. You have vision disturbances

People with hyperthyroidism often complain about blurred vision, even dry or irritated eyes, Dr. Bier says. People who have severe hyperthyroidism in a condition called Grave’s Disease could also have bulging eyes, which eye doctors call proptosis.

19. You're having irregular heart rhythms

Lying in bed or sitting at a desk shouldn’t make your heart race, except if you have hyperthyroidism. With this condition, excess thyroid hormone can make your heart beat faster, leading to palpitations, even an irregular heartbeat which could put you at risk of a potentially dangerous condition called atrial fibrillation (afib). Afib can occur in approximately five to 15 percent of patients, especially older individuals, Dr. Pessah-Pollack says. Complications of atrial fibrillation in people with hyperthyroidism include heart failure and blood clots.

20. You feel weak

Don’t be surprised if you go to lift a heavy object and can’t or have trouble doing mundane things like climbing stairs. Dr. Bier says weakness is a sign of hyperthyroidism.