Hot Yoga: Is It Safe and Can You Lose Weight Doing It?

April 23, 2016

I have had clients tell me that the idea of practicing yoga sounds great, but doing it in a room that is around 105 degrees for 60-90 minutes? Well, for many that sounds dreadful.

But while sweating enough to water your garden doesn’t quite sound like a relaxing afternoon, it can do more than simply provide relaxation. For most, once they try it, they actually fall in love with the practice — hence the enormous popularity of hot yoga, also known as Bikram yoga. What does the research say? Let’s take a deep look into hot yoga, and see if the benefits match the hype.

What Are the Benefits of Hot Yoga?

Times Magazine reported a study that was conducted by Brian L. Tracy, PhD, an exercise scientist at Colorado State University. Dr. Tracy conducted two experiments regarding the physical effects of Bikram yoga, a branded style of hot yoga, which involves completing a strict series of 26 poses over a period of 90 minutes in a room heated to about 105 degrees. (1)

The first experiment included healthy young adults with no yoga experience and who did little to no exercise on a regular basis. The young adults were assessed after eight weeks and 24 Bikram sessions. Participants did, in fact, show 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. While this was good, it wasn’t as great as expected since hot yoga feels as though you are working really hard.

Dr. Tracy felt he needed to know more, so he conducted a follow-up experiment with experienced yogis. This time, he hooked them up to equipment designed to measure their heart rates, body temperatures and energy expenditures during a typical 90-minute hot yoga session. This data helped explain why some of the previous participants had less weight loss than originally expected. While heart rate and core temperature increased, their metabolic rates, or the amount of calories their bodies burned, were roughly the same as someone who took a brisk walk.

Regardless, hot yoga has been popular for some time. Forbes notes that hot yoga has grown into a $6 billion business, in particular, through some branded names. Harvard Business School Professor, Rohit Deshpandé, shared some information about what seems to be the two most popular yoga brands: Bikram Yoga, founded by Bikram Choudhury, who has worked towards a patent of his approach to yoga; and Tara Stiles, who focuses more on integrating yoga with different types of exercises movements to create a beneficial exercise program. (2)

In another report, Dr. Tracy conducted experiments to track the calorie burn of hot yoga, which typically boasts a rather large number. Athletes that were tested reported burning as many as 1,000 calories during a single 90-minute yoga session, according to Tracy. However, his study of the physiological responses of 11 female and eight male participants, between the ages of 18 and 40, found a different and less significant result. Women came in at about a 330 calorie burn, while men hit about 460 per 90-minute session. (3) Needless to say, that’s still a decent workout and doesn’t speak to the mental/spiritual benefits that its proponents testify about.

In general, yoga was once viewed skeptically in terms of its health benefits, but over time, it’s gained respect as a great way to help relieve stress and improve health and well-being, even through the meditation opportunities it can provide. It is even recommended by some physicians for patients who may be at risk for heart disease, as well as those with back pain, arthritis, depression and other chronic conditions.

History of Hot Yoga

Stone carvings, found in archeological sites and dating back 5,000 years or more, have been discovered depicting figures in yoga positions. It is a common misconception that yoga is rooted in Hinduism; however, Hinduism’s religious structures evolved much later and incorporated some of the practices of yoga as did many other religions throughout the world. (4)

One of the earliest texts having to do with yoga was compiled by a scholar named Patanjali, possibly as early as the 1st or 2nd century B.C. and is known as “Ashtanga Yoga,” or the eight limbs of yoga, and is usually referenced as Classical Yoga today.

Yoga probably arrived in the U.S. in the late 1800s, but it did not gain popularity until the 1960s. Most often viewed as an ancient tradition, yoga has now become even more common amongst a huge part of society from housewives to hipsters, from male to female, from young to old and from runners to all athlete types. In fact, is not uncommon to find a “yoga for runners” type yoga class at your neighborhood studio or nearby gym since it’s great for flexibility, opening the hip flexors and possibly preventing common running injuries.

In the U.S. alone, about 16 million Americans practice yoga every year, usually in group classes with a certified yoga teacher. However, yoga entrepreneurs have branded their own styles of practice, from Bikram’s 105 degree workout rooms to studios that offer “doga,” a practice of yoga together with one’s dog. (5) (6)

The Differences in Hot Yoga and Power Yoga

Both hot yoga and power yoga help you develop strength, relieve stress and help with flexibility, and both come with their challenges. Here is a list of some notable differences to help you consider the style that may be best suited for you.

Hot Yoga (similar to Bikram)

Hot room that is around 104–105 degrees/40 percent humidity.
26 specific postures and 2 breathing exercises in a specific order, chosen by founder of Bikram, Bikram Choudhury. He claims that these postures work every part of the body, giving it everything it needs to “maintain optimum health and maximum function.”
Bikram brought his form of yoga to the United States in 1973.
Bikram is a rule-based practice.
Official studios must have carpeting and mirrors on the front wall of the room only.
Bright lighting is required throughout class.
No hands-on adjustments are allowed.
Bikram classes are always 90 minutes.
Teacher instructs from the front of the room only.
There is no music during a Bikram class.
Poses are held for a specific amount of time and do not flow together.
Hot yoga uses breathing techniques called 80-20 breathing or exhalation breathing, depending on the posture.

Power Yoga (similar to Vinyasa)

Moderately heated temperatures.
Postures vary according to the designs style of the instructor and presented in a challenging series.
Power yoga is the westernized version of Ashtanga Vinyasa yoga, a form developed by Pattabhi Jois in Mysore, India.
Beryl Bender Birch and Brian Kest, Ashtanga experts, developed “Power” yoga when they started teaching Ashtanga-influenced styles in the late 1980s.
Baron Baptiste is another well-known practitioner of the Power yoga style.
Power yoga does not provide strict guidelines.
Classes can be any length.
The studio can have any type of flooring and lighting.
The instructor or location can choose the music.
You will typically go through traditional poses such as Sun Salutations, Downward-Facing Dog and Warrior, flowing seamlessly from one pose to the next.
Vinyasa refers to the process of breathing and moving from posture to posture, which is an important characteristic of Power yoga.
The flowing, heat-promoting breath called Ujjayi is used in which you inhale and exhale rhythmically through your nose. (7)

Is Hot Yoga Safe?

There is no doubt that yoga offers many benefits due to the breathing exercises that provide healthy meditation and the flexibility that can be gained, popular even for runners, but is it safe?

The American Council on Exercise (ACE) sponsored research that examined heart-rate and core-temperature responses to a 90-minute hot yoga style class. As previously noted, the typical session is 90 minutes long, in a room heated to about 105° F and 40 percent humidity and mostly consist of various yoga poses and a few breathing exercises. If you have ever taken one of these classes, you have probably found yourself completely drenched in sweat and may even be surrounded by your own sweat puddles, which for some, is a rather cleansing feeling.

But the essence of hot yoga, for many hot yoga enthusiasts, is the mental strength and focus required to endure the workout in the heat all while doing the poses using the best form possible. This is part of what makes it exciting and even addictive. Those that love this intensity claim improved mindfulness, flexibility, strength, muscle tone and general fitness as a direct result of practicing this form of yoga.

“Research conducted in the past few years has provided some support for these claims, while also finding benefits in the form of lower perceived stress levels, improved cardiorespiratory endurance and improved balance, as well as increased deadlift strength and shoulder flexibility, and modestly decreased body-fat percentages.” (8) It has even been suggested that yoga help those at high risk of developing metabolic disease due to improved overall glucose tolerance and insulin resistance.

So, yes, it is likely that you will gain all of those benefits, but it’s the heat that researchers are trying to gain a better understanding of. ACE asked John P. Porcari, Ph.D., and his team of researchers at the University of Wisconsin, La Crosse’s Department of Exercise and Sport Science to learn more. They did this by recruiting 20 apparently healthy volunteers, 7 males and 13 females, ranging in age from 28 to 67 years old. All participants were practiced hot yoga on a regular basis; therefore, they were familiar with the standard poses and the hot and humid environment.

Before participating in the session, which was conducted by a certified instructor, each participant swallowed a core body temperature sensor and was given a heart-rate monitor to wear during the yoga class. Core temperature was recorded before the class began, and every 10 minutes throughout the session. Heart rate was recorded every minute during the class and session ratings of perceived exertion (RPE). Additionally, using the Borg 1–10 scale, which is a way of measuring the intensity of a physical activity, RPE levels were recorded at the end of class. (9)

Heart rate varied depending on the difficulty of the pose being performed. Core temperature steadily increased throughout the class for both genders; however, heart rate, maximum heart rate and RPE were consistent between both men and women. The average heart rate was near 80 percent of the predicted maximum heart rate for males and about 72 percent for females. The highest heart rate recorded during the class among the male participants was 92 percent, and 85 percent for the females.

The average highest core temperature for men was 103.2 ± 0.78° F and 102.0 ± 0.92° F for women, though a couple of participants reached a slightly higher temperature. Even though there were no signs of heat intolerance, core temperatures that reach these numbers can be problematic for some participants and both the National Athletic Trainer’s Association (NATA) and the American College of Sports Medicine (ACSM) state that exertion-related heat illness and heat stroke can occur at a core temperature of 104° F, so core temperatures should be considered.

The concern lies greatly in the fact that these temperatures are rising without a lot a movement because they focus primarily on balance and strength rather than cardiovascular training. And while the sweating can release toxins, it’s not doing the primary job, which is to cool the body when heated. (10)

How to Safely Take a Hot Yoga Class

Ultimately, you need to pay attention to your body. If you feel lightheaded, you may want to step out of the room, though many classes are not fond of any interruptions; find out the rules. There are five key things you can and should do to keep your class safe and beneficial at the same time.

Take a shorter version of the class. In the study, the dangerous core temperatures occurred at about 60 minutes into the class. By shortening the duration of the class, it could help minimize the heat-induced risks but still provide the useful benefits noted above.
Keep the room at a lower temperature. For example, take yoga classes that are around 98–100 F vs the common 105 degree temps in some classes. Though some may feel that this takes away from the purpose of hot yoga, you can often derive the same benefits while still sweating profusely! In fact, many studios at full-service gyms prefer these slightly lower temps.
Hydrate more frequently. There is some controversy about how water breaks disrupt the focus of the practice for the individual and for those around them, but we all know that hydration is very important in all forms of exercise. You may want to consider finding a yoga instructor that encourages hydration throughout the class.
Listen to your body. If you feel lightheaded, nauseous, confused, or have muscle cramps during or after a yoga practice, those may be signs that you need to reduce your time spent in yoga practice or even eliminate it altogether.
Replace nutrients. It’s very important to learn how to stay hydrated, but keep in mind that you can lose a lot of nutrients with an excessive sweat session. Oftentimes, participants will only replace the water, but don’t realize that they are at dangerously low levels of potassium, sodium and other electrolytes. Coconut water and a banana can help replace these nutrients. (11)

Risks of Hot Yoga + Precautions to Consider

Always take precautions and consult your doctor before trying any new exercises program, especially if you have a history of diabetes, cardiovascular or respiratory disease, or any heat-related illness. Make sure you are well hydrated before, during and after your practice. Leave the room immediately if you feel any symptoms of heat exhaustion, such as dizziness, nausea, headache, confusion, poor vision or weakness.