Are You Always Cold? 9 Possible Reasons You're Chilly All the Time

You Naturally Run Cold

You've likely heard someone say they just "run cold," and there's some real truth to that. According to Aarti Agarwal, M.D., board-certified internist at Juno Medical, says, some people do actually run cold, and therefore always feel cold.

"In the absence of any medical reason, some people do tend to feel colder than others most of the time," she says. (Note that she says in the absence of any medical reason. That means this persistent feeling of cold isn't tied to an underlying health condition.)

So why does this happen? It could be due to lower muscle mass, according to Dr. Agarwal. "Some people have lower muscle mass relative to body surface area," she says. "Muscles generate heat, and if you have lower muscle mass, the body tends to conserve heat by diverting blood flow away from the extremities." This can cause your hands and feet—and maybe your entire body—to feel cold.

And yes, some people are at higher risk of "running cold" than others: "Women and older people tend to have lower muscle mass, and these groups tend to 'run cold,'" Dr. Agarwal says.

Lack of Sleep

Some science has suggested that a severe lack of sleep can actually cause you to feel cold more frequently. The how and why of it is a little complicated. Your body's sleep cycle is regulated by your circadian rhythm—sometimes called your body's internal clock. It's an internal schedule that helps your body understand when it's supposed to go to sleep and when it's supposed to wake up. Both internal and external cues like light, temperature, and hormones help tell your body what to do.

When your circadian rhythm thinks it's time to go to sleep, your body does a few things. Your brain releases melatonin, a hormone that promotes sleep, and your internal temperature will drop. "The circadian rhythm causes our body temperature to drop during sleep," Dr. Agarwal says. "If you're awake at a time that your body thinks you should be asleep...you'll likely feel colder than usual."

In other words, you might feel colder during the day because you're so tired that your body thinks it's time to go to sleep.

Poor Circulation

Your circulatory system is responsible for circulating blood throughout your body. If you have poor circulation it means your blood isn't flowing as freely or as effectively as it should. "Blood vessels can constrict (restricting blood flow) or dilate (increasing blood flow)," Dr. Agarwal explains. "If blood flow is restricted to certain parts of the body—usually [the] hands and feet—those areas will feel cold."

According to Dr. Agarwal, there are many different reasons why you might have poor circulation. Risk factors include smoking and obesity—as well as some underlying health conditions. And if you're interested in improving your circulation, you can try to do some basic things—like exercising regularly, eating a healthy diet, and refraining from smoking. You can also visit your doctor to find out whether your poor circulation is tied to another health condition.

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Rapid Weight Loss

Some research has suggested that rapid weight loss might actually cause you to feel cold more frequently. There are two reasons behind this. "First, subcutaneous fat (fat that's under your skin) acts as an insulator against cold and helps conserve heat," Dr. Agarwal says. When you lose weight, you may lose some of this fat, and since it acts as an insulator, you'll also be losing some of what keeps you warm. "[Second], if you decrease your calorie intake dramatically, your body's metabolism will slow down to conserve energy," Dr. Agarwal says, which can cause you to feel cold more frequently.

Vitamin B12 Deficiency

Vitamin B12 plays a role in several of your body's key functions. It keeps your nervous system in tip-top shape and helps your body produce DNA and RNA. Vitamin B12 is naturally found in a variety of foods—including tuna, tofu, salmon, beef, milk, and cheese—and adults need about 2.4 micrograms of it per day. (For context, that's the amount of vitamin B12 found in two cups of whole milk or in 3 ounces of ground beef.)

Since vitamin B12 is easily accessible and found in many foods, most people in the U.S. do get enough of it. However, some are at higher risk of experiencing vitamin B12 deficiency than others. Since vitamin B12 is primarily found in animal products, for instance, vegans and vegetarians may need to supplement their intake to make sure they're getting enough of this important nutrient. Others may include adults over the age of 50, people with pernicious anemia, people who have recently undergone gastrointestinal surgery, and people with digestive disorders.

Vitamin B12 Deficiency symptoms:

• Fatigue
• Weakness
• Constipation
• Appetite loss
• Weight loss
• Megaloblastic anemia (which can cause you to feel cold)
• Feelings of being cold, tingling, or numbness (especially in the hands or feet)

Hypothyroidism

If you have hypothyroidism, you have an underactive thyroid. Your thyroid is a small gland that produces hormones that affect the way your body uses energy. An underactive thyroid means your thyroid gland isn't producing enough hormones to meet your body's needs. And one of the symptoms associated with hyperthyroidism is cold intolerance.

Hypothyroidism can be caused by a number of different health conditions, and it can also be the result of certain kinds of treatment (like surgery and radiation). You may be at higher risk of experiencing hypothyroidism if you're a woman, over the age of 60, have experienced thyroid issues in the past, or have certain underlying health conditions (like type 1 diabetes or lupus).

Anemia

Anemia is a blood disorder that occurs when you don't have enough healthy red blood cells to circulate oxygen throughout your body, and there are many different kinds of anemia. It can be caused by blood loss, and it can also happen when your body doesn't produce enough red blood cells—or when it destroys too many of them. Along with fatigue, shortness of breath, headaches, and other symptoms, anemia can cause cold hands and feet. And you may be at higher risk of experiencing it if you are pregnant, have heavy periods, or are deficient in certain nutrients (like iron, folic acid, and vitamin B12).

Blood Vessel Disorders

A couple of different blood vessel disorders have been linked to cold intolerance. These include: Peripheral Arterial Disease and Raynaud's disease.

Peripheral Arterial Disease (PAD) is the result of your blood vessels becoming so narrow or blocked that they can't carry blood from your heart to your other organs. This can be caused by fatty plaque building up in your arteries (a condition that has its own name: atherosclerosis). PAD typically affects the legs or the arms. And you may be at higher risk of experiencing it if you smoke, have high blood pressure, have diabetes, have high cholesterol, or are over the age of 60.

Another condition linked to cold intolerance is Raynaud's disease, a rare blood vessel disorder that typically affects the fingers and toes. If you have Raynaud's disease, your blood vessels may constrict when you're cold or stressed—causing a lack of circulation to certain parts of your body (like your fingers and toes). The scientific community is still working to understand what causes Raynaud's disease, but they do know it can be caused by injuries, certain health conditions, and certain medications. You may be at higher risk of experiencing Raynaud's disease if you're a woman, over the age of 30, have a family history of the disease, or live in a place with a cold climate.

Diabetes

Diabetes is a health condition characterized by too-high glucose levels. It happens when your blood sugar (blood glucose) is too high. There are two kinds of diabetes: type 1 diabetes and type 2 diabetes. If you have type 1 diabetes, your body doesn't produce insulin—a hormone that allows your body to use glucose as energy. If you have type 2 diabetes, your body doesn't produce or use insulin well. Feelings of coldness, numbness, or tingling, especially in the feet or hands, is a symptom associated with diabetes.