Hot Yoga: What the Heat Does, and What It Does Not

Published on 14 October, 2026

Hot yoga has one claim at its center: that practicing in a heated room makes the practice work better. That claim has now been tested directly, by randomizing people into the same yoga sequence performed at 105 degrees Fahrenheit and at ordinary room temperature.

What Hot Yoga Is

The term covers two quite different things, and studios use it loosely.

Bikram yoga is a specific, standardized system: twenty-six postures and two breathing exercises, always in the same order, over ninety minutes, in a room held at 105 degrees Fahrenheit, which is about 40.5 degrees Celsius, at around 40 percent humidity. The sequence never varies.

Hot yoga more broadly means any style run in a heated room, most often a flowing or power sequence, usually somewhere between 90 and 100 degrees Fahrenheit, and typically sixty minutes rather than ninety. Classes vary enormously because the only shared element is the thermostat.

The Study That Tested the Heat Itself

Almost all research on hot yoga compares it against doing nothing, which cannot separate the effect of the yoga from the effect of the heat. One trial was designed specifically to settle that question.

Fifty-two sedentary but healthy adults aged 40 to 60 were randomized into three groups: the Bikram sequence practiced at 40.5 degrees Celsius, the identical Bikram sequence practiced at 23 degrees Celsius, and a sedentary control. Both yoga groups did ninety-minute classes three times a week for twelve weeks. The outcome measured was endothelium-dependent vasodilatation, which is how well the lining of the blood vessels responds and is among the better early markers of cardiovascular health.

Both yoga groups improved, and they improved by a similar amount. The authors concluded that the postures produce the vascular benefit regardless of room temperature, and that their findings downplay the necessity of the heated environment.

If your reason for choosing a heated class is cardiovascular health, the evidence says the heat is not the active ingredient. If your reason is that you enjoy it, that is a perfectly good reason and nothing above argues against it.

What the Heat Genuinely Changes

The heat is doing three things, none of which is what it is usually credited with.

It raises tissue temperature and stretch tolerance. Warm muscle lengthens more easily, and the perception of a stretch is less sharp when you are hot. You will reach further in a hot room. Whether that produces more lasting flexibility than warming up properly in a cool one has not been well demonstrated.
It raises heart rate and perceived effort at the same workload. Working to cool yourself puts a load on the cardiovascular system. The session feels much harder, which many people find satisfying, but a harder-feeling session is not automatically a more productive one.
It produces a great deal of sweat. Measured sweat rates in a Bikram class run around 0.6 kilograms an hour in novices and 1.1 in experienced practitioners. That is fluid loss.

Sweat is temperature regulation. It is not a route for eliminating toxins, which is work done by the liver and the kidneys, and the weight lost during a hot class is water that returns as soon as you rehydrate. A class that leaves you two pounds lighter has not removed two pounds of anything but fluid.

What It Does for Fitness

A randomized trial of eight weeks of Bikram training in healthy young adults measured a range of fitness outcomes. Deadlift strength improved, lower back and hamstring flexibility improved substantially, shoulder flexibility improved, and body fat decreased modestly. Handgrip strength did not change, cardiovascular measures did not change, and maximal aerobic fitness did not change.

The summary the authors gave is the right one: the gains were specific to the training stimulus. Hot yoga builds flexibility and some strength. It is not a substitute for aerobic exercise, and anyone relying on it for cardiovascular fitness is better served adding walking, cycling or swimming alongside it.

The Thousand Calorie Claim

Studios have long advertised hot yoga as burning up to 1,000 calories a session. A laboratory study put twenty-four practitioners through a standardized ninety-minute Bikram class in an environmental chamber with expired gas collected throughout.

Mean energy expenditure was 286 calories for the full ninety minutes, with a range across individuals of 179 to 478. Every posture in the sequence was classified as light to moderate intensity by American College of Sports Medicine standards. The 1,000 calorie figure is not close to accurate, and it is roughly three to five times the real number.

The authors' own conclusion was measured and fair: a light to moderate intensity session, practiced several times a week, could contribute to weight maintenance or weight loss. That is true of most regular movement, and it remains a reason to practice.

Stress and the Nervous System

A sixteen-week randomized trial in sixty-three stressed and sedentary adults tested Bikram yoga against no treatment, measuring heart rate variability as the primary outcome. There was no significant difference between the groups on heart rate variability or on any secondary measure.

Within the yoga group, people who attended more classes did show reductions in diastolic blood pressure and body fat percentage. That is an association rather than a randomized comparison, and the honest reading is that attendance mattered and the intervention as delivered did not beat the control on its primary outcome.

Safety, Which Deserves More Space Than It Usually Gets

Most people practice hot yoga without incident. The risks are specific and avoidable.

Heat illness. Dizziness, nausea, headache, confusion, clammy skin or stopping sweating are all signals to leave the room immediately rather than to push through. Standing still and feeling faint in a 105 degree room is not a sign of mental weakness.
Dehydration. Losing over a kilogram of fluid in a class is routine. Drink before, during and after, and judge the following day by urine color rather than by thirst, which lags behind.
Low blood sodium. Replacing heavy sweat losses with plain water alone, repeatedly, can dilute blood sodium. It is uncommon but serious. People sweating heavily and practicing often should include some sodium, which a normal meal or an electrolyte drink supplies.
Overstretching. The heat removes some of the discomfort that normally tells you to stop. Working to a depth your joint is not conditioned for is the most common way people hurt themselves in a hot class.
Pregnancy. Raising core body temperature is not advised in pregnancy, particularly in the first trimester, and heated classes are generally contraindicated.

Hot yoga is also a poor choice for anyone with cardiovascular disease, uncontrolled blood pressure, a history of fainting, multiple sclerosis where heat worsens symptoms, or who takes medication affecting fluid balance or sweating, including diuretics and some antidepressants and antihistamines. The sensible step is a conversation with the doctor who manages your care, not a cautious first class.

What Ayurveda Says About It

Pitta is the dosha associated with heat, intensity and drive, and it is aggravated by more of the same. A person already running hot, irritable, competitive and inflamed is the person most likely to be drawn to a demanding class in a hot room, and is the person it will suit least.

For a pitta constitution, or for anyone in a period of heat and overdrive, the traditional guidance is to practice cool, early or late in the day, and well short of exhaustion. That advice happens to align with what the vascular trial found: you can take the same sequence into a room at ordinary temperature and get the same measurable benefit.

Practicing Sensibly

Hydrate across the day before a class rather than drinking heavily in the ten minutes before it starts.
Take the back of the room for your first few classes, where the air is cooler, and plan to sit a posture out rather than treating that as failure.
Leave the room if you feel dizzy, nauseated or confused. Cool down, rehydrate, and do not go back in during that session.
Replace sodium as well as water if you sweat heavily and practice often, through a normal salted meal or an electrolyte drink.
Stay within the range you can reach in an unheated room. The extra depth the heat allows is not matched by conditioning in the joint.
Add separate aerobic exercise if cardiovascular fitness is your goal, since the trials show hot yoga does not deliver it.

What This Means for an Unheated Practice

Hot yoga is not among the styles taught at YO1. The sessions cover Hatha, Restorative, Ashtanga, Kundalini, Yin and pranayama-led practice, with instructors adapting each one to the guest in front of them. The trial described earlier is the reason that is not a gap: the same sequence performed at an ordinary room temperature produced the same improvement in vascular function as the heated version did.

What a stay adds is not intensity but consistency and supervision. Practicing daily for several days, with someone correcting what you are doing, tends to be worth more than a harder class taken occasionally.

Book Your Wellness Journey at YO1

Yoga at YO1 is taught daily across several styles, with certified instructors guiding each guest according to their comfort and ability. Every stay opens with a personal wellness consultation with a Health Counselor, and the therapies and meals follow from it.

To plan a stay built around what you have come for, visit yo1.com.

FAQs

Q: Is hot yoga better than regular yoga?

A: Not for cardiovascular benefit. A randomized trial ran the same Bikram sequence at 40.5 degrees Celsius and at 23 degrees Celsius and found similar improvements in blood vessel function in both groups, which suggests the postures rather than the heat are doing the work. The heat makes the session feel harder and lets you stretch further in the moment, and some people genuinely prefer it.

Q: How many calories does hot yoga burn?

A: Far fewer than studios advertise. A laboratory study measuring oxygen uptake through a full ninety-minute Bikram class found an average of 286 calories, ranging from 179 to 478 across individuals. The widely repeated figure of 1,000 calories has no support, and every posture in the sequence rated as light to moderate intensity.

Q: Does hot yoga detox your body?

A: No. Sweating is how the body sheds heat, not how it clears toxins, which is work done by the liver and the kidneys. The weight lost during a hot class is fluid and it returns with rehydration.

Q: Is hot yoga good for weight loss?

A: Modestly, and mainly as a form of regular movement rather than because of the heat. One eight-week trial found a small decrease in body fat alongside gains in strength and flexibility. Energy expenditure per class is in the range of a brisk walk of similar length, so it helps most as part of a wider routine.

Q: Who should avoid hot yoga?

A: Anyone pregnant, and anyone with cardiovascular disease, uncontrolled blood pressure, a history of fainting, or a condition such as multiple sclerosis where heat worsens symptoms. Several common medications, including diuretics and some antidepressants and antihistamines, affect fluid balance or sweating and warrant a conversation with your doctor first.

Q: What should I drink before and after a hot class?

A: Hydrate steadily through the day before, rather than in a rush beforehand. Drink during and after. If you sweat heavily and practice several times a week, include sodium through a salted meal or an electrolyte drink, because replacing large sweat losses with plain water alone can dilute blood sodium.

Q: Does hot yoga make you more flexible?

A: You will reach further during a hot class, because warm tissue lengthens more easily and the heat blunts the sensation of a stretch. Trials do show real flexibility gains from regular practice. Whether the heat adds flexibility beyond what a proper warm-up in a cool room achieves has not been clearly demonstrated.

Q: Is Bikram the same as hot yoga?

A: Bikram is one specific system: twenty-six postures and two breathing exercises in a fixed order over ninety minutes at 105 degrees Fahrenheit. Hot yoga is a general term for any class in a heated room, usually a flow sequence, often shorter and at a lower temperature. All Bikram is hot yoga; most hot yoga is not Bikram.

Q: What does Ayurveda say about hot yoga?

A: It advises caution for anyone of a pitta constitution or in a heated, overdriven state, on the principle that heat added to heat aggravates rather than balances. The traditional guidance is to practice cool, early or late in the day, and to stop well short of exhaustion.

Q: Can beginners do hot yoga?

A: Yes, with sensible precautions. Take the back of the room where it is cooler, expect to sit postures out, hydrate well beforehand, and leave the room if you feel dizzy or nauseated. If you are new to yoga altogether, learning the postures in an unheated class first is easier and safer.

Sources

Hunter SD, et al. Effects of yoga interventions practised in heated and thermoneutral conditions on endothelium-dependent vasodilatation: The Bikram yoga heart study. Exp Physiol. 2018. PMID: 29349832
Tracy BL, Hart CEF. Bikram yoga training and physical fitness in healthy young adults. J Strength Cond Res. 2013. PMID: 22592178
Pate JL, Buono MJ. The physiological responses to Bikram yoga in novice and experienced practitioners. Altern Ther Health Med. 2014. PMID: 25141359
Hewett ZL, et al. Effect of a 16-week Bikram yoga program on heart rate variability and associated cardiovascular disease risk factors in stressed and sedentary adults: A randomized controlled trial. BMC Complement Altern Med. 2017. PMID: 28431533

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