It happens a lot. I'm in a yoga class, really aiming to do precisely what the teacher says. That is, visualize my breath flowing through my body down to my toes and into the tips of my fingers. I let go of any angry thoughts. I relax my jaw. And then it happens. I can't help but think what would make this wonderfully together and peaceful and grounded and full of inner-happiness yoga instructor really lose it.
Now I know.
A book about the science of yoga. Oxymoronically as it may seem, a gaggle of yoga teachers have bombarded William J. Broad, a New York Times science writer and author of The Science of Yoga with hate mail. One of them, he told NPR, even used the "F" word in an email. As in "F You Bill Broad!"
While this comprehensive book covers everything from the titillating orgasmic history of yoga to its impact on mental and physical health, Broad rankled quite a few yogis, it seemed, with two findings:
1. Yoga's slow deep meditative breathing does not rev up your metabolism. In other words, yoga in and of itself is not the quick fix to weight loss.
2. Ineffective teachers can push you into dangerously contortionist poses. In other words, beware: You can get hurt.
Let's focus on point one. While a lot of yoga classes today, as Broad points out, have morphed more into old-fashioned feel-the-burn exercise classes, the traditional body-stretching yoga poses combined with super-slow deep breathing will not help you burn calories. They are not aerobic. The meditative breathing, science has shown, may even put you into a deeply relaxed state which has just the opposite effect on you compared with, say, going out for a run. I'm not sure why that shocks anybody or really what the fuss is all about. If your yoga teacher is really skinny, then he or she is probably doing something else other than deep breathing and it probably has to do with what they are eating -- or not eating.
The science though is fascinating: A 2006 study of more than 100 men and women in Bangalore found that regular yoga practice cuts basal metabolic rate by about 13 percent. Even more so among women than men. It seems that the slow breathing techniques hit the autonomic nervous system which influences, among other things, the way you burn energy. The investigator concluded that yoga "creates a propensity for weight gain and fat deposition." On a positive note, a 2009 study at the University of Pennsylvania found that this very same slowing-down yoga phenomenon was good for heart health. Blood pressure declined, they found, among 26 volunteers doing Iyengar yoga -- a slow sort of practice.
But before you worry about weight gain, Broad points out that the practice of yoga -- regardless of the specific physiologic effects -- may put you in a better mental state so you will stick to your diet better than if you hadn't done yoga in the first place.
And point two: Every form of exercise class -- whether it be Tai Chi or spinning -- has terrific teachers who show you how to do things correctly. And like everything other body-movement class, there are lousy coaches who may encourage you to try something you shouldn't. If you are twisting your body into a pretzel or trying to stand on your hands and it just doesn't feel right, chances are it isn't right for your body. You could get hurt. That doesn't seem very newsy or anger-provoking to me.
Broad, as he states clearly, is a yoga enthusiast and has been doing it for some 40 years. And yet, all the buzz about slower metabolism and potential hazards misses out on the juicy bits in his book.
For one, yoga may improve your sex life.
Indeed, one of the main reasons yoga was invented in the first place, according to The Science of Yoga, was to help men in Indian reach a truly orgasmic state. Hatha Yoga Pradipika, an ancient yoga text, focuses, as Broad writes, on parts of the body not usually mentioned in today's yoga classes. Those authors talk about sitting postures that add pressure (good stimulating pressure) to the vagina, penis, scrotum, and anus. I've done yoga for years -- not nearly as long as Broad -- and I can't remember any teacher using the word vagina.
He points out medical imaging studies have shown that the brains of expert yogis in deep yoga mode look remarkably like the brains of people in sexual climax. A study of a dozen young men, conducted in 1974, found that months of yoga increased testosterone excretion by more than 50 percent. Of course, these studies are far from conclusive, but they do hint at happier endings than the fat-deposition ones.
Maybe some of these hormonal changes -- if they are truly significant changes -- may explain why some people feel that yoga has helped them cope better with depression. Again the studies are murky, but offer, at least, an alternative therapy to treating mental illness.
It's hard to believe that an experienced yoga practitioner and Pulitzer Prize-winning author can inspire such ire, particularly when he concludes his book with a huge endorsement: Yoga, he says, "can turn our bodies into customized pharmaceutical plants that churn out tailored hormones and nerve impulses that heal, cure, raise moods, lower cholesterol, induce sleep, and do a million other things. Moreover, yoga can do it in an extremely low cost with little or not risk of side effects."
Maybe those angry yogis never finished the book. Or maybe they need to practice their breathing techniques along with a Happy Baby pose.
Follow Randi Hutter Epstein, MD, MPH on Twitter: www.twitter.com/randihepstein