By Diana Bruk
If you work out in hot weather, science says you’ll burn more fat and build more muscle than if you did the same routine at cooler temperatures.
Thanks to a recent study, we know that people burn more calories when they exercise in the cold than in comfortable temperatures, due to a process called thermogenesis, a metabolic activity that burns extra calories just to keep your body warm. But what about exercising when it’s super hot outside?
We already know that, contrary to common opinion, sweating doesn’t actually help you burn more calories, because you’re just releasing water weight (it does, however, help remove toxins from your body). Still, one can’t help but notice that running, or even walking up a hill, in 35-degree weather feels a lot more strenuous than on a cool, cloudy day. So you figure it must burn more calories, right?
Indeed it does. One 2010 Spanish study, for example, found that cyclists who exercised in 40 degree weather burned more fat and increased more muscle than those who did the same exercise at the same intensity at 20 degrees.
Given that exercise already makes your body temperature rise, your body also burns more calories as it tries to cool your body temperature in extreme heat, a process known as thermoregulation. A person’s average body temperature is between 36.6°C and 37.7°C, which is a pretty narrow window. If it falls any lower than 35°C, you could suffer from hypothermia. If it gets any higher than 42°C, you could get brain damage or even die. So when you raise your body temperature in extreme heat, your body needs to work harder to achieve homeostasis.
It should be mentioned that exercising in extreme heat carries some drawbacks. Studies have found that people can do longer workouts in cooler temperatures than in hotter ones, which is why your gym blasts the AC. It’s also worth noting that exercising in extreme heat can be dangerous, leading to dehydration, sudden dizziness, and nausea. When exercising outside in hot weather, it’s crucial to stay hydrated and stop if you start to feel unwell.
Still, it’s nice to know that even that strenuous walk to the car or public transit to commute to work on a hot day isn’t all for nothing.