Doctors Share Why You ‘Run Hot’ Or ‘Run Cold’

You probably know ― or maybe even are ― one of those people who’s always hot or always cold. You may have even uttered the phrase “I run hot” or “I run cold” as those around you experience the opposite reaction to the weather.

And if you’ve ever been told to just put on a sweatshirt or had a loved one roll their eyes at that phrase, we have some validation for you.

Experts say there are many reasons behind this phenomenon. Some people do just run hot or cold based on their physical makeup, while others may be dealing with some underlying, and oft-treatable, medical conditions.

Here’s what to know:

Your habits and body makeup can contribute to a feeling of always being hot or cold.

“I think the first thing just to understand is that humans can regulate their body temperature, regardless of their environment,” said Dr. Heather Viola, an internal medicine doctor at Mount Sinai Health System in New York. “And where that starts is with your autonomic nervous system — that’s the part of the nervous system that controls automatic functions … like breathing, or sweating for that matter, and this process starts in the brain, where hormones are released to control temperature.”

She noted that there are a number of things that can alter the release of these hormones and make you feel hot or cold more often than not. This can include stress levels, whether or not you smoke, your diet and your muscle mass.

“A lot of people, when they’re under stress, can definitely perceive that they’re more hot than those around them,” Viola said. “I think the same thing can be said for if you consume spicy food, or caffeine or even a lot of alcohol, it can also affect your autonomic nervous system and raise your heart rate.” This makes you feel hotter.

Viola said the more body fat you have, the warmer you may feel. “This may be why a lot of older people feel colder than younger people,” Viola said. “Just because the fat layer under the skin that conserves heat can thin as people get older.”

Certain medical conditions can also cause temperature changes.

It’s also important to know that certain medical conditions can contribute to your perceived temperature. According to Viola, a low body mass index or struggles with anorexia can cause one to feel cold.

Issues with your thyroid levels also can be a factor, said Dr. John Schumann, the Oklahoma-based executive medical director of Oak Street Health.

If you have low thyroid hormone levels, you’ll likely feel cold more often than hot, according to Schumann. If you have high thyroid hormone levels, the opposite will be true. These conditions are often treatable through medication.

Schumann added that anemia may be another reason for temperature problems. “The symptom of it could be that someone feels cold all the time,” he said — but he stressed that not everyone with anemia feels cold.

More often than not, in Schumann’s experience, patients who complain of always being hot or always being cold have nothing medically going on under the surface. If you do feel that you are always hot or always cold ― and are worried about it ― it’s certainly worth talking to your doctor. That’s especially the case if other issues accompany this always-hot or always-cold feeling, like changes in your bowel movements, fatigue, and skin or hair changes, Viola said.

If this temperature problem interferes with your day-to-day routine, it’s also worth paying your doctor a visit, she added.

All in all, feeling hot or cold all the time is legit — and there is a reason why you feel that way.

“It doesn’t always come down to a medical condition,” Voila said. But “I wouldn’t say somebody runs hot for no reason. … I would say there [are] underlying reasons physiologically, and usually comes down to your body habits.”

So, the next time someone makes fun of you for being cold on a hot day or sweltering in the middle of winter, know that it may not just be all in your head.