Is hot yoga good for you?

Bikram yoga mightn't be as great for you as you think...Photography Getty Images

Hot yogis sing the praises of Bikram but research has found working out in a room heated to 40 degrees isn't all it’s cracked up to be.

A new study found Bikram yoga may not be as effective for weight loss as first thought, with participants burning the same amount of kilojoules as those walking briskly.

As one of the first published studies looking into the effects of Bikram yoga, Dr. Brian L. Tracy, an exercise scientist at Colorado State University and his team of researchers conducted two experiments on Bikram’s physical effects, which involves completing a series of poses over a period of 90 minutes in a room heated to 40 degrees celsius.

The first experiment included healthy young adults with no yoga experience. After eight weeks and 24 Bikram sessions, the study participants showed some modest increases in strength and muscle control, as well as a big improvement in balance. They also achieved a slight drop in body weight.

“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,” said Tracy. “And remember, these were people who didn’t regularly exercise before the study. We were expecting a bigger drop.”

For his follow-up experiment, Tracy hooked up experienced yogis to equipment designed to measure their heart rates, body temperatures, and energy expenditures during a typical Bikram session. That new data helped explain some of those disappointing body-weight findings: while heart rate and core temp climbed significantly during the 90-minute session, the participants’ metabolic rates - or the amount of calories their bodies burned - were roughly equivalent to those of people walking briskly.

This is disappointing news if you’re a Bikram fan.

Several articles have led yogis to believe they could be burning up to 4000 kilojoules a session, but research has found that’s not the case, with the study showing men burn an average of 1900 kilojoules, while women work off about 1300.

“I think the heat and the difficulty of the postures combine to alter your perception of the intensity of the exercise,” Tracy explains.

On the other hand, one part of your body is getting a major workout, he says. “Heart rates are quite high for the amount of work you’re doing.”

The humidity in Bikram studios is supposed to be kept at 40 percent, but in reality, it’s tough to know how often that goal is achieved or maintained. As the humidity climbs and your heart keeps working to cool you off, you’re sweating out minerals like potassium and sodium, along with H20, so being mindful of heat and humidity is imperative. After all, water alone can't replace lost minerals.

And don't forget, that your kidneys and liver do the bulk of detoxing - no amount of sweating could ever match their performance.

To protect yourself, pay close attention to your body. Feelings of light-headedness, nausea, confusion, or muscle cramping - either during or after a yoga practice - are all signs that you need to take a break.

Left unanswered are questions about the long-term effects of hot yoga practice, or how people with heart defects or other health conditions might react to the strenuous conditions, Tracy says.

Sweat sessions aside, most hot yoga fans also praise the mental and psychological benefits. And a growing pile of research on yoga suggests the practice - and not just the hot varieties - may help lower stress while improving pain management and emotion regulation in ways similar to meditation.