Perception of Effort, or Calorie Burn in Hot Yoga

“How many calories will I burn?”

“Will I lose weight?”

These are, by far, the two most popular questions I hear from new Bikram Yoga students. And really, when you get right down to it, they are the same question – “I want to lose weight by burning a lot of calories – will I do that?”

The answer people WANT to hear is: YES, you will burn a TON of calories and you will lose weight, you betcha, I promise! (Also, would you like to buy some magic beans??)

The real answer: IT DEPENDS.

If you understand general fitness principles, metabolic rates, and how the human body works, you’ll know that calorie burn for any activity is very, very individual – and based on more factors than your average online calorie calculator can account for. Intensity matters, heart rate matters, overall fitness matters, lean body mass matters, overall bodyweight matters, consistency matters.

[I realize that by saying that, I really need to write up a more general post about calories, metabolic rates, and misconceptions. In the meantime, here is one of several posts about calories from my friend GoKaleo.]

The assumption, with hot yoga, is that the perceived intensity equals higher calorie burn. It’s a hot room, you feel your heart pounding, you are sweating head to toe, you are thirsty – all of those are signs of intensity, so you must be working really hard. You assume you MUST be burning calories at a much higher rate than you would if you were just doing “regular” yoga or walking.

I have seen hyperbolic claims of anywhere from 500 to 1200 calories burned, during one 90 minute Bikram Yoga class.

If the activity you are doing SEEMS really difficult, does it rate a higher calorie burn?

In the past few years, there have (finally!) been serious clinical studies of hot yoga.

In one study, sponsored by the American Council on Exercise (ACE), participants took the same 60 minute yoga class – first in a “cool” room (about 70 degrees F), then in a “hot” room (about 92 degrees). Researchers found only slight differences in heart rate or core temperature for participants between the two classes – but the perception of effort was much higher in the hot yoga class.

Two studies, headed by Dr. Brian Tracy of University of Colorado, have focused on Bikram Yoga, specifically. The room temperature for a Bikram Yoga class is around 105 degrees F. In the first study, perception of effort and intensity by participants was high, but there was only a small drop in body weight (after 8 weeks and 24 classes) despite all participants having been sedentary before joining the study.

“To be honest, we were pretty surprised by the small size of the weight change, because when you’re in the Bikram studio you feel like you’re working really hard,” Tracy says. “And remember, these were people who didn’t regularly exercise before the study. We were expecting a bigger drop.”

So in the second study, they measured heart rate, core temperature, and energy expenditure. The conclusion: heart rate and core temperature went up, and energy expenditure was about the same as if the participants were walking briskly (about a 3.5 mph rate).

“I think the immediate reaction is disappointment if you’re a Bikram fan,” Tracy says, adding that, if you’ve spent time reading about the activity online, you might assume you’d be shedding up to 1,000 calories per session. “But that’s not the case,” he says. His research shows men burn an average of 460 calories, while women work off about 330. “I think the heat and the difficulty of the postures combine to alter your perception of the intensity of the exercise,” he explains.

The perceived intensity of the activity did not match the actual calorie burn rate.

Actual calorie burn rate for a Bikram Yoga class is about the same as a brisk walk.

I have seen this dismissed by people in the yoga community because it doesn’t match the more hyperbolic claims we’ve heard in the past. When you’ve believed for years that your chosen form of activity burns calories at almost mythic rates, “brisk walk” sounds insignificant and ludicrous.

This rate of calorie burn is NOT insignificant. It is not hyperbolic, it is not MYTHIC – but it is reasonable.

If your goal is to achieve some weight loss, and this is an activity you enjoy, go ahead and do some hot yoga.

Keep your expectations realistic. Ignore the hype and hyperbole.

If you like it, do it!

You don’t need hype to move your body.

By the way, if you’ve ever tried to maintain a brisk walking pace for 90 minutes, you know it’s nothing to scoff at.

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