Do you burn more calories when it's hot out? What a dietitian has to say

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As temperatures soar, you’re probably breaking a sweat walking from your house to your car. Not to mention the hot and humid weather makes it feel like you’re working harder during exercise. But does that extra sweat on your brow equate to burning more calories in the hot summer sun? Ahead, experts answer your questions.

Do you burn more calories in the heat?

The body works very hard to maintain a steady internal temperature of around 98.6 F. This is a physiological process called thermoregulation. If the body senses that its internal temperature is rising, sweat glands activate to perspire and keep the body cool. Sweat evaporating from the skin cools you down.

Regardless of how hot or sweaty you feel, the body does a good job of staying cool. It doesn’t require more calories to produce sweat, and, therefore, you don’t naturally burn more calories in the heat.

Some people produce more sweat than others, but there isn’t any research to suggest that more sweat equates to a higher calorie burn.

However, higher sweat rates do increase the risk of dehydration.

“When it is very hot out, people may sweat a lot which puts them at risk for dehydration,” says Dr. Marc Eisenberg, clinical cardiologist and associate professor of medicine at the Columbia University Medical Center in New York.

“When you’re dehydrated, blood pressure may drop and, in response to a low blood pressure, one’s heart rate may increase to compensate for the low blood pressure,” adds Eisenberg. He notes that an increased heart rate doesn’t translate to a great calorie burn either. In addition, this elevated heart rate is dangerous.

“If you are unable to produce sweat (because you are dehydrated) or your sweat doesn’t evaporate due to high humidity, you may lose the ability to cool off quickly, thus placing you at risk for developing heatstroke,” says Eisenberg. This is why most people complain of feeling warmer than the actual temperature on very humid days.

“During heatstroke, one’s body temperature rises to 104 F or above, causing confusion and irritability, as well as possible slurred speech, seizures and coma,” notes Eisenberg.

But there is some good news — the body adapts to the heat after about 14 days. Research suggests that the human body acclimatizes to hot conditions and feels a lower level of perceived exertion during exercise in hot climates. In other words, you may start to feel better in the heat after two weeks. Yet, it’s still incredibly important to hydrate in hot weather, even if you’re heat-adapted.

Do you burn more calories when it's hot or cold?

You won't burn more calories in the heat, but that may be a different story in cold weather. According to the National Institutes of Health, the body works very hard to maintain its internal body temperature in both hot and cold environments.

Yet, when it's cold, heat loss occurs and the internal body temperature drops, the hypothalamus (a small region in the brain) increases the body’s metabolism to generate heat. In addition, the muscles involuntarily contract to cause shivering and generate heat. Shivering also burns calories.

However, a drop in body temperature or shivering only occurs in extreme and potentially life-threatening circumstances. Living in a cold climate does not necessarily translate to calorie burn.

Does exercising in the heat help you lose weight?

You may notice that the scale is slightly lower after exercising in the heat, but that’s most likely due to a loss of water weight. Increased heat causes the body to sweat more to keep itself cool. If you don’t drink water and electrolytes to replace the sweat you're losing, you may lose a few pounds of water weight and become dehydrated.

Eisenberg warns that exertional heatstroke can occur in healthy people participating in strenuous exercise on very hot days, too. “For those of you who are insistent on playing [a sport] l during a heatwave, taking frequent breaks (preferably in an air-conditioned room) and drinking plenty of fluids are of paramount importance,” says Eisenberg.

This article was originally published on TODAY.com