Constantly feeling cold is not only uncomfortable, but it could be a sign of an underlying health problem like hypothyroidism, a vitamin deficiency, or simply not getting enough sleep.

Feeling chilly when you're outside in the cool weather is one thing, but if you're always shivering while everyone else say they're toasty, then it's time to investigate. Here are 10 possible causes for why you're always so cold, and how you can get a handle on your out of whack internal thermostat.

why am i always cold , Mature woman wrapped in a blanket and looking at her mobile phone while sitting in stylish bed
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1. Low Body Weight

Low body weight—defined as a BMI hovering around 18.5 or under—can keep you feeling cold for a couple of reasons.

First, when you're underweight, you lack an adequate level of body fat to insulate you from cold temperatures, Maggie Moon, RD, a Los Angeles–based nutritionist, tells Health.

Plus, A low BMI usually means a reduced food intake. Skimping on calories slows your metabolism so you don't create enough body heat.

If you suspect your chills are due to being underweight, you may experience other symptoms, such as:

How to treat it: If you're underweight, talk to your doctor, who will run tests to see what's causing your low body weight. They may also suggest you put on a few pounds by loading up on whole, healthy foods that contain lots of protein, fat, and complex carbohydrates.

2. Hypothyroidism

"Always being cold is a telltale sign of hypothyroidism, which means your thyroid doesn't secrete enough thyroid hormone," Holly Phillips, MD, an internist at Lenox Hill Hospital in New York City, tells Health. Without the right level of this hormone, your metabolism slows, preventing you from generating adequate heat.

Approximately 4.5% of Americans have this condition, and rates are higher in women who were recently pregnant or are over age 60. Other signs of hypothyroidism include:

How to treat it: If you suspect a thyroid problem, see your doctor, who can confirm the diagnosis with a blood test and treat the condition with prescription meds.

3. Iron-deficiency anemia  

Low iron levels are one of the most common reasons for chronic coldness. That's because iron helps red blood cells carry oxygen throughout your body so it's able to produce heat, Dr. Phillips explains. Iron is also crucial because a deficiency can slow thyroid functioning, leading to hypothyroidism—which further leaves you freezing, Moon says.

According to the National Heart, Lung, and Blood Institute, other symptoms of low iron levels include:

How to treat it: First you'll want to get a proper diagnosis via a blood test at your doc's. Then, depending on the severity of your anemia, they may suggest you take iron supplements, get an IV infusion, or simply boost your intake of iron-rich foods like red meat, leafy greens, and eggs, says Moon.

4. Poor circulation

If your hands and feet are ice-cold but you otherwise feel toasty, then a circulation problem that keeps blood from reaching your extremities may be to blame.

One common cause of circulation problems is Raynaud's disease, sometimes called Raynaud's phenomenon, which affects 5% of the US population, according to the National Heart, Lung, and Blood Institute. This condition causes the blood vessels in your hands and feet to temporarily narrow when they sense cold, Margarita Rohr, MD, internist at NYU Langone Medical Center in New York City, tells Health.

Other reasons blood may have a hard time reaching your limbs include cardiovascular disease, which causes your heart to not pump as effectively, or smoking, which constricts blood vessels, Dr. Rohr says.

How to treat it: While most people with Raynaud's rarely need treatment, some may want to go on medication. Pay a visit to your primary care physician, who can determine the cause of your circulation problems and make sure it's not something more serious like cardiovascular disease.

5. Dehydration

If you just can't warm up, it could be a signal you need to drink more water. "Up to 60% of the adult human body is water, and water helps regulate body temperature," says Moon. "If you're adequately hydrated, water will trap heat and release it slowly, keeping your body temperature in a comfortable zone. With less water, your body is more sensitive to extreme temperatures."

Beyond feeling chilly, other symptoms of dehydration include:

  • Lightheadedness or confusion
  • Muscle cramps
  • Constipation
  • Dark-colored urine

How to treat it: Aim for eight glasses a day at a minimum, recommends Moon, but always drink more if you're working out or spending time in the sun.  

6. Vitamin B12 deficiency  

Not consuming enough vitamin B12—about 2.4. micrograms daily for the average adult—can cause anemia, resulting in chronic coldness, Moon says. If you experience the following symptoms in addition to constant chills, you may have a B12 deficiency:

  • Numbness or tingling in the hands, legs, or feet
  • A swollen and inflamed tongue
  • Balance problems
  • Memory loss

How to treat it: While B12 deficiency is rare in the general population, it's common among vegans or vegetarians since the nutrient is almost exclusively found in animal products, Moon says. Therefore, try taking a supplement if you're plant-based. Otherwise, check in with your doctor, as it may be a sign of an absorption issue.

7. Being a woman

Do you ever find yourself battling male family members or colleagues about who should control the thermostat? Turns out feeling cold really is a gendered condition.

While it may seem counterintuitive, women are better at conserving heat than men because the female body maintains blood flow to vital organs like the brain and heart, says Dr. Rohr. However, this means less blood reaches your hands and feet, leaving them constantly cold.

How to treat it: If cranking up the thermostat isn't an option, socks and gloves are your best friends in this situation. Or invest in a small space heater for your desk.

8. Diabetes

Diabetes that's not kept in check can lead to a condition called peripheral neuropathy, which damages the nerves in your hands and feet.

"When this develops, you experience numbness and sometimes pain in the hands and feet, and since these nerves are also responsible for sending messages to the brain regarding temperature sensation, your hands and feet may feel cold," Dr. Rohr says.

How to treat it: Diabetic nephropathy develops gradually, so you may not realize you have it. But if you are diabetic or have symptoms of the disease, like frequent urination, fatigue, and feeling parched, see your doctor.

9. Minimal muscle mass

If you've already paid a visit to your physician for your incessant chills and they've determined you don't have an underlying condition, you may be cold due to lack of muscle mass.

Muscle helps maintain body temperature by producing heat, says Dr. Rohr, so not having enough muscle tone contributes to feeling frosty. Also, having more muscle mass fires up your metabolism, which fights the perma-freeze feeling.

How to treat it: Hitting the weight room at the gym or investing in free weights will help build muscle to power your furnace.

10. Lack of sleep

Not getting enough sleep wreaks havoc on your nervous system, which can throw your temperature regulating systems all out of whack, Dr. Phillips says.

While it's not clear why this happens, not getting enough snooze time reduces activity in the hypothalamus, the part of your brain that controls body temperature. Plus, when you're fatigued from a restless night, your metabolism works at a more sluggish pace, says Dr. Phillips.

How to treat it: Make sure you're getting the recommended seven to nine hours of sleep a night, sticking to a regular sleep schedule, and powering off electronics about 30 minutes before your head hits the pillow.

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