hot yoga | worth the hype?

hot yoga | heat, health and hype

I’m about to start teaching at a hot yoga studio and realised - I didn’t actually know why it needed to be hot. Curious about the science behind the sweat, I went looking for evidence (as usual). Conveniently, a new systematic review (Willmott et al., 2025) analysed 43 studies and 942 participants to uncover the acute and long-term effects of hot yoga. In this article, I explore its origins, what counts as ‘hot’, the evidence-based benefits, and whether it’s truly better than unheated yoga, before sharing my own take.

How hot?

Hot yoga is a style of yoga practised in a heated room, typically between 30–40 °C with moderate humidity (~40%). The goal is to combine traditional yoga postures and breathing techniques with heat-induced physiological stress.

Origins 

While inspired by traditional Indian yoga, the heated-room concept is a modern Western innovation. Hot yoga evolved from Bikram Yoga, developed in the 1970s by Bikram Choudhury, an Indian-born teacher who introduced his practice to California. Choudhury claimed that practising yoga in a heated environment enhanced flexibility and mental discipline through physical endurance. Bikram Yoga gained global popularity through the 1990s and 2000s, until allegations of abuse and misconduct against Choudhury emerged in the 2010s (Ernesto, 2015). In response, many studios rebranded as “hot yoga,” keeping the heat but distancing themselves from the Bikram name.

What the Science Says

This article is inspired by a recent systematic review by Willmott et al. (2025) summarising evidence from 43 studies involving 942 participants (76% female). Studies included yoga practised at ≥25 °C for at least 20 minutes (acute) or repeated sessions (chronic), and measured outcomes in physiological, functional, or psychological and cognitive domains.

Key Findings

Acute Effects (Single Session)

• Hot yoga increases body temperature and heart rate, adding thermal stress on top of physical exertion.

• Energy expenditure was not consistently greater in hot yoga vs unheated (same calories burned)

Chronic Effects (Repeated Practice)

Physiological adaptations

• Body composition – mostly no change. One study found reduced body mass and BMI in obese older adults specifically, but body fat percentage itself didn't shift in most studies.

• Lipid profile – mixed, and worth a closer look than "inconsistent" suggests. In older adults, LDL ("bad" cholesterol) dropped without touching HDL — a clean win. In younger adults, total cholesterol dropped too, but so did HDL ("good" cholesterol) — which isn't a clear improvement overall.

Functional / Performance Adaptations

• Increased flexibility with heat - most consistent finding - repeated hot yoga improves range of motion and joint flexibility.

• Several studies observed enhanced balance and proprioception, potentially aided by heat, which increases muscle relaxation. (The "heat relaxes muscles" explanation is my own guess at the mechanism, not something the review itself tested — worth holding loosely.)

• Evidence is mixed for increased muscle strength and endurance – some improvements reported in the submaximal strength test.

• Improved Bone Mineral Density (BMD) - evidence is preliminary - a single study reported positive changes in bone mineral density, especially in lower limbs and spine; however, a single small longitudinal study (n = 9, no control group, Bikram teachers over 5 years).

• Slight improvements in submaximal exercise performance (how efficiently your body can perform before hitting fatigue) after several weeks of hot yoga. No consistent evidence that maximal aerobic capacity (VO₂ max) improved significantly. 

Psychological/cognitive adaptations

• Multiple studies reported reductions in stress, anxiety, and depressive symptoms after several weeks of hot yoga (typically 6–12 weeks, 2–5 sessions/week). Potential mechanisms involved: social engagement, mindfulness and breath control, mild heat stress. However, the effect of heat alone is unsubstantiated.

• Cognition is essentially unstudied for hot yoga specifically — only one small trial exists (women with ADHD, 6 weeks of Bikram yoga), and it found no change in inhibitory control, cognitive flexibility, or working memory versus a waitlist control. It's plausible that the focus required by controlled breathing and sustained postures trains attention over time, and that lower stress indirectly helps cognitive performance — but that's speculation on my part, not something this review found. Nowhere near enough evidence to claim hot yoga improves cognition.

Overall, hot yoga shows interesting adaptations and health/functional benefits, but claims that it is "better than regular yoga or other exercise" are unsubstantiated and warrant further research. The authors emphasise several methodological limitations, such as small sample size and the lack of non-heated yoga controls. Also, not accounting for female menstrual cycle fluctuations and do not an even split between male and female. In conclusion, new research should include better experimental design and more mechanistic investigations (explain why observed changes occur) to strengthen the evidence.

Bottom Line

In short, hot yoga may improve flexibility, balance, body composition, some cardiovascular markers, and well-being — but there’s not enough evidence to say it’s superior to unheated yoga.

Caution

Hot yoga combines exercise with heat stress, so hydration, pacing, and gradual acclimation are key. Those sensitive to heat — including older adults, individuals with cardiovascular conditions, or those on certain medications — should seek medical advice before participating. 

Opinion

My view is that there’s enough evidence to justify giving hot yoga a try for about six weeks and seeing how your body responds. Be cautious if you’re sensitive to heat, and seek medical advice if you’re unsure. But if you don’t have access to a heated studio, don’t sweat it. Your regular unheated practice offers many of the same benefits.

Have you tried hot yoga? Let me know your thoughts.

- Sophia

References 

Ernesto, L. (2015). Visits to My Bikram Yoga Studio Have Become a Walk of Shame [New York Times]. https://www.nytimes.com/2015/03/02/opinion/visits-to-my-bikram-yoga-studio-have-become-a-walk-of-shame.html

Willmott, A. G. B., James, C. A., Jewiss, M., Gibson, O. R., Brocherie, F., & Mee, J. A. (2025). Hot Yoga: A Systematic Review of the Physiological, Functional and Psychological Responses and Adaptations. Sports Medicine - Open, 11(1), 110. https://doi.org/10.1186/s40798-025-00917-7