The Evidence Is in: Yoga Can Protect You Against Disease

The intent of yoga is to create well-being as a result of physical, emotional, mental, social, and spiritual balance. This is also the intent of medicine, as defined by the World Health Organization. While the entire focus of yoga is to create such a balance to prevent diseases, yoga can be used to cure or manage diseases as well.

A general feature of yoga practice—including asana, pranayama, and meditation—is its capability of inducing a coordinated psychophysiological response, which is the antithesis of the stress response. This “relaxation response” consists of a generalized reduction in both cognitive and somatic arousal, as observed in the modified activity of the hypothalamic pituitary axis and the autonomic nervous system. Basu Bagchi and M. A. Wenger, in their early yoga research, wrote, “Physiologically, yogic meditation represents deep relaxation of the autonomic nervous system without drowsiness or sleep.”

A large number of subsequent research studies examining the effects of these techniques, both in isolation and in combination, have further confirmed these early results. Yoga practice is most typically associated with reductions in the levels of the stress hormones cortisol and the catecholamines; a decrease in sympathetic activity, with a corresponding increase in parasympathetic activity; reductions in metabolic rate and oxygen consumption; and salutary effects on cognitive activity and cerebral neurophysiology.

The first systematic medical application of yoga started in India in 1918, at the Yoga Institute at Versova near Mumbai. This was soon followed by clinical work at the Kaivalyadhama Yoga Institute in Lonavala under Swami Kuvalyananda in the 1920s. Subsequently, yoga therapy has proliferated in India with the establishment of yogic hospitals and clinics and the widespread application of yoga treatments by clinicians and yoga institutes. This trend has also spread internationally, with the appearance of yoga therapy centers, the inclusion of yoga programs in hospital cancer programs and affiliated alternative medicine centers, and the establishment of yoga therapy training programs and the International Association of Yoga Therapists.

This movement in yoga therapy comes at a time when noncommunicable diseases (NCDs) are the leading cause of death in the world. According to the World Health Organization, 40 million people die each year from NCDs, mainly from cardiovascular diseases, cancers, chronic respiratory diseases, and diabetes. More than 14 million of those deaths occur between the ages of 30 and 70, of which 85 percent are in developing countries. In most middle- and high-income countries, NCDs are responsible for more deaths than all other causes of death combined; in the United States, NCDs are estimated to account for more than 88 percent of total deaths. That number is projected to increase by 15 percent globally between 2010 and 2020.

Yoga research offers a different set of statistics—one that has the potential to counteract this catastrophic trend. In a national survey of yoga practitioners’ mental and physical health, compared to national norms, practitioners reported better sleep, higher energy level, healthier weight, better relationships—and 86.5 percent reported they were happier because of practicing yoga. A study that I cofacilitated showed that increased yoga experience predicted lower body mass index and reduced medication use in women ages 45 and older. This is just a tiny fraction of a growing body of research on yoga’s effects on gene expression, mood state, brain structure and function, and brain biochemistry, among many other areas of study. This work is making an impact on how the healthcare field views yoga. For example, Medicare now reimburses for Dean Ornish’s cardiac yoga program.

As yoga practitioners have always known, intuitively and experientially, yoga doesn’t just make you feel good. These practices have real, concrete results for the mind and body—they positively impact everything from the brain and biochemistry to BMI and blood glucose levels. This is not a placebo effect; you don’t have to “believe" in yoga for it to work. When you practice regularly over a significant period of time, these changes will occur.

Find out about programs on the science of yoga with Sat Bir S. Khalsa at Kripalu.

© Kripalu Center for Yoga & Health. All rights reserved. To request permission to reprint, please e-mail

Sat Bir S. Khalsa, PhD, is associate professor of medicine at Harvard Medical School, editor-in-chief of the International Journal of Yoga Therapy, and chief editor of the medical textbook The Principles and Practice of Yoga in Health Care.

Full Bio and Programs