Sweating it out on the lava-like floor of a hot yoga studio can make you question a lot of things: can they turn down the heat, whether that pose is even possible, and if you're actually burning more calories by doing this in the sweltering heat. Sure, you're sweating more, but lots of sweat isn't a requirement for losing weight. What kind of a calorie burn can you expect from hot yoga anyways, in comparison to a unheated practice?
"It has become a popular belief that hot yoga is good for weight loss, but this is not scientifically backed with relation to hot yoga specifically," said Julia Kelley, a registered yoga teacher who's trained in hot yoga. "Yoga itself will burn calories, but hot yoga is not proven to burn more calories than a nonheated Vinyasa class."
That doesn't mean hot yoga can't be good for your calorie burn and weight-loss goals. The high temperature forces your body to work harder to cool itself off (also called thermoregulation), which increases your heart rate, said Jorianne Numbers, MS, an exercise physiologist at Northwestern Medicine. A 2002 study published in Medicine & Science in Sports & Exercise supports that heat can lead to more weight loss, showing that you burn more fat for fuel in hot temperatures.
There's also the fact that your muscles are more pliable in warmer temperatures, Jorianne said. That makes it easier to stretch and hold poses for longer, which can positively impact calorie burn. Julia also told POPSUGAR that, "Hot yoga, specifically power yoga, may encourage you to work your muscles a bit harder, which may lead to burning more calories to a comparative Vinyasa class where you don't feel as challenged." However, much of that might be a mental effect of feeling like you're should push yourself harder in the warm, sweaty environment than a physical reaction to the heat, she explained.
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Finally, Jorianne said, practicing in a hot room can cause you to focus more on breathing deeply. That's great for your overall lung capacity, improving your performance in cardio (and calorie-burning) activities like walking and running. "Any yoga practice where you are engaging in breath practices will be beneficial to the oxygenation of your body, which can assist with weight loss," Julia added. In fact, the oxygen you breathe in and carbon dioxide you exhale also has a part in weight loss, according to a 2014 study; the majority of weight you lose isn't simply "burned up" into nothing, but
exhaled in the form of CO2.
The puddles of sweat on your yoga mat, though, don't actually have much to do with it. "Sweating is the body's way of regulating body temperature," Jorianne explained. When you sweat, you're losing "water weight," which means you'll gain it back naturally when you rehydrate. (Something you definitely need to do after an exhausting hot yoga session.)
So while there are some physical aspects of hot yoga that can help you with your weight-loss goals, we actually don't have any proof that a heated yoga class will burn more calories. Julia recommended it to anyone looking for a physical and mental challenge in their practice, especially for beginners looking to improve their flexibility. And we'd be remiss if we didn't mention the mental benefits, which can positively impact your weight loss, too. By reducing stress and promoting mindfulness, Jorianne explained, a practice like hot yoga might help you become more conscious of what you're putting in your body.