CHAPTER 5

How Yoga Works Deep Inside Your Body

WE HAVE NOW reviewed some of the trenchant arguments for doing yoga. American yoga has grown from 20.4 million practitioners in 2012 to 36.7 million in 2016. Over 100 million Americans have tried yoga at home. There are more Americans doing yoga than there are in some prominent Christian denominations.¹

Yes, yoga is that popular. Yet, of course, there are an even larger number of people who have not tried it. Yoga Journal and Yoga Alliance have teamed up with Ipsos Public Affairs to find out why some people—some of whom could certainly benefit from its weight-loss properties—shy away from yoga.² Here are the five main reasons, along with rejoinders that hopefully will help persuade the skeptical.

1.“I’m not sure if it is right for me.” Answer: There’s only one way to find out.

2.“I don’t know how to get started.” Answer: This book contains advice and encouragement. Keep reading!

3.“I don’t exercise.” Answer: Yoga is not exactly exercise in the usual sense, though when doing poses you are exercising. Still, this may be the right moment to begin to move and stretch.

4.“I feel out of place in a yoga class.” Two answers: There are so many yoga teachers and so many yoga classes that there are very likely at least a few that are right and comfortable for any given individual. Also, the instructions in this book can be carried out at home and done almost entirely on your own.

5.“My body is not right for yoga.” Two answers: Yoga practitioners of so many different “body types” exist right now that it’s unlikely yours is not among them. Also, yoga harmonizes, coordinates, and unifies you and your body, so even if yours were a “non-yoga body,” the practice of yoga would likely transform it and change that.

Unlike most of the current methods of weight loss, yoga is practically free, currently requires no license to practice or teach, and has such beneficial “side effects” as more elegant posture, better balance, greater range of motion, improved strength, finer coordination, lower anxiety, and all the other curative properties we reviewed in chapter 1. It is silent, requires no paraphernalia, and is easy to remember. So how, in detail, does yoga transform you from a person who is bigger than you may want to be to someone in your desired range?

YOUR BRAIN AND STOMACH “TALK” TO EACH OTHER

To evaluate the role of yoga in weight loss, we must recognize that the brain, among its many functions, is also part of the digestive apparatus—a good part of why we eat as we do, act as we do, and therefore weigh what we weigh.³ The illustration on the facing page shows what the stomach, the organ inside us, looks like; it also indicates where the receptors lie, and a few of their linkages with the brain. In the picture, CNS abbreviates “central nervous system.”

This linkage I refer to isn’t only from the stomach to the brain. It includes the part of the esophagus just north of the stomach, and the first part of the duodenum, the intestinal beginnings past the exit-hatch from the stomach. Stretching the stomach and these parts just a little promotes the secretion of the enzymes that aid in digestion: histamine and gastrin and pepsinogen. It also causes the stomach’s muscles to contract. However, with an increased stretch—more than just a little—the opposite occurs: cholecystokinin and adiponectin hormones emerge. Miraculously, this cuts down the activity of the digestion mechanism and speeds fat metabolism. At the same time the hunger-stimulating hormone ghrelin diminishes sharply, further damping down the desire to eat.⁴ Further, and most important, stretching the intestinal, esophageal, and stomach receptors propagates direct feedback to the appetite centers in the brain, inhibiting their function. These stretches rapidly cut down appetite. We immediately become less hungry. Yes, stretching the stomach enough by doing rather simple yoga can actually decrease your desire to eat!

The flexible digestive system

As it turns out, stretching the stomach radially, as if inflating a balloon in the stomach, or eating a large meal, has much more effect on your appetite than stretching this organ the long way—top to bottom.⁵ That is exactly what yoga does—stretches the stomach radially.

Focusing down more finely than anatomy, we enter histology, the study of tissues—the aspect of live things that are smaller than organs but larger than cells. These are groups of cells, with their surrounding self-manufactured extracellular elements. Here we can really understand how and why and where and when stretching the tissues of those organs—the lower esophagus, stomach, and upper duodenum—has the greatest effect on appetite.

The duodenum is bound down to the rest of the body at two points, lower down at the hepatoduodenal ligament, where the duodenum gets closest to the liver, and higher up, by the fascia that encompasses the head of the pancreas. See the picture on page 35 for details. When you arch your back, those two points move apart, and the characteristic duodenal arch becomes somewhat flattened. Such stretching is well within the “normal range of motion” of these organs.

Studies have refined the observations made here about the stomach. Let me mention a few of them here to attempt to entice you into learning more about this convenient relationship between stretch and slimness. Actually, a number of animal studies find that stomach stretch is the most important factor in limiting appetite.⁶ Some researchers have genetically “removed” this feedback-system loop, which controls appetite in fruit flies. Result: The altered fruit flies are “supersized.”

Part A in the illustration shows a fruit fly without a feedback loop from the stomach to the brain. Part B shows a normal fruit fly.

Fruit flies with and without appetite feedback loop

YOUR SENSES AND EMOTIONS HAVE PHYSICAL EFFECTS

Yet another wonderful and related action takes place when you do yoga. It happens subtly, even without your assent: You are suddenly paying more attention to yourself and everything else. You are more conscious, just plain more aware. This new sensitivity has two aspects: Interoception involves those sensations that come from inside you, be it your joints, your sinuses, or your stomach. Exteroception involves sensing your environment, including the heat of the day, the sidewalk under your feet, and everything else you feel with your skin, see, hear, smell, and taste. It may not seem obvious, but the yogic heightening of interoceptive acuity is useful for reducing your appetite and losing weight. It supplies another route in addition to the physical stretch, which makes you less hungry.

Many studies confirm that yoga improves interoception, making you more informed of your bodily state and sensations. In other words, the yoga here not only stretches the appetite-curbing receptors but also makes you more keenly responsive to your newly lowered impetus to eat. Yoga becomes a self-enhancing ally in the quest for caloric limitation, a system going in the right direction—toward less food.

NIGHTTIME EATING AND CALORIES YOUR BRAIN CAN BURN

Yoga lowers anxiety, and anxiety can be related to eating long after the regular dinner hour. Some people maintain that eating late at night has a very big effect on your weight. A calorie is a calorie is a calorie, but there is some truth in this: The stretch receptors in the duodenum, stomach, and lower esophagus suppress appetite only one-fourth as powerfully at midnight as they do at noon. So if you go down for a snack in the wee hours of the morning, you’ll be likely to eat a substantially greater amount than would satisfy you at lunch. Moreover, the lack of sleep, and the anxiety about facing tomorrow without enough of it, may further prompt you to overeat.⁷ Higher anxiety is associated with higher levels of ghrelin, the fat maker, and lower levels of leptin, adiponectin, and the other slimming hormones.⁸ You can calm down with yoga.

It is also well documented that your brain is a major calorie burner. I find it amazing that our brains use an estimated 20 percent of the calories we consume, which is another way the brain is linked to the stomach. There are Tibetan yogis who direct their scantily clad acolytes to meditate in the wintry mountain forests, and estimate their proximity to enlightenment by how much snow has melted around them. Yogis may or may not be able to voluntarily stop their hearts, but there is little doubt that they can start their heads, that they can just sit there, apparently motionless, and burn calories.

Actually, yoga styles range from the highly energetic and metabolically demanding regimens of B.K.S. Iyengar and K. Pattabhi Jois to the calmly reflective lagoons of meditation. Some styles of yoga can raise your heart rate, and presumably the rate at which you’re turning calories into energy plus carbon dioxide plus water. This, of course, burns calories. Every type and tradition of yoga involves some exercise. Recent science finds that exercise of the yogic kind (as well as other kinds) brings about cellular changes that play right into the plans of those who need and want to control their weight. Contemporary science has solidly proved two such changes, one in the cell, and one within its nucleus.

THE MORE MITOCHONDRIA, THE BETTER FOR WEIGHT LOSS

When it comes to the cell, I am referring to a molecule with the eminently forgettable name of peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha), a fearsome intracellular warrior that reduces arthritis and inflammation of all kinds, and lowers the risk of Alzheimer’s disease, heart disease, and a number of cancers. It also accelerates the proliferation of mitochondria, the fat burners of our bodies.⁹ Telling you something about the mitochondria here makes sense, since they are almost universally believed to be the strongest ally, in a sense the only ally, of all of us who want to lose weight.¹⁰ And by far the strongest stimulus to create more mitochondria is PGC-1alpha.

Mitochondria originated with a symbiotic relationship between a bacterial and an animal cell. This began when Earth was at least a billion years younger than it is today. The most favored theory is that mitochondria stem from a bacterial cell that was engulfed by an animal cell and for some reason was not digested by the animal cell. Instead, it survived within the animal cell. Before long the bacterial DNA was supplying the animal cell with energy that gave that particular cell a distinct advantage over others. After a while, only these bacterially fortified cells and their progeny survived. The animal cells and the smaller bacterial cells within them had managed to help each other, the bacteria giving the animal cells more energy, and the animal cells protecting their small internal power stations from the great world beyond.

The mitochondria developed over the course of time to supply the cells with almost all their energy, and with that support, the cells specialized into liver, retina, and all the other fabulously coordinated functionality of complex animals and humans. Although both the cells’ nuclei and the mitochondria have DNA, neither could get by, neither could live, without the other. Most of the proteins that mitochondria use come from the cells’ nuclei and the DNA in the nuclei. But energy is developed almost solely in the mitochondria, and the structures that produce it come from the mitochondrial DNA. Cells that use more energy have more mitochondria. One liver cell is estimated to have two thousand. Heart muscle may be 40 percent mitochondria. Mitochondria are 10 to 12 percent of our human body weight!

A mitochondrion, power station of all cells

On the molecular level, we really run on electricity. Our hearts contract with the use of electrical impulses, our nerves conduct along very close analogues of electric wires, and our muscles are soft electric motors that ratchet rather than spin. The mitochondria do all the electron transferring. And the more mitochondria there are, the more energy that becomes available for everything we do. Yoga induces your body to release more PGC-1alpha, which induces more mitochondria, which in turn changes more glucose into energy. This makes for a slimmer, more energetic person.

How does PGC-1alpha make for more mitochondria? True to their bacterial origins, mitochondria can glom together and also divide quite independently of the cells that host them. If the DNA or other structures in a single mitochondrion are damaged or degraded, the mitochondrion finds a way to combine with another healthy one to restore their all-important function. If the cell is in need of more energy, there are mechanisms within the cell that prompt the mitochondria to split in two and thus increase their numbers. As is so frequently the case in nature, there are checks and balances. Each cell also generates forces that limit the number and activity of the mitochondria. But the prime factor for increasing their number is PGC-1alpha.

So what does this mean for the person intent on losing weight? More, and more active, mitochondria translate directly into a more energetic, more metabolically active life. The greater the number of mitochondria in your liver, the better it functions, handling glucose production and use, and secreting enzymes to digest fats. More mitochondria in cartilage cells means healthier and better-moving joints that are less susceptible to arthritic degradation. The same goes for stronger and more resilient tendons, a more accurately responsive immune system, a more finely regulated thyroid gland, extra-retentive memory cells, and more-discriminating appetite centers in your brain. It makes for a higher-functioning you. When it comes to weight loss, you use additional calories to live better and you become a higher-functioning organism.

Mitochondrial enrichment is about as deep-seated and pervasive a change as anyone can make. Yoga usually slows your metabolism while you are doing it, but after practicing it for some time, it raises your energy utilization generally. Saying that yoga cannot help you lose weight because it lowers your metabolism is similar to saying that higher education cannot improve your income because when you’re in school you make no money and in fact have to pay for it. On the contrary, yoga enables you to convert calories into a better and finer life for yourself.

Physicians are fond of saying, “As you get older, your metabolism slows down,” to account for what has been called middle-age spread. There are many reasons for this change in so many people’s bodies, including less sharply discriminating sensory perception, which leads to poorer responsiveness in the appetite centers. But with the aid of additional mitochondria, all of these functions are actually raised back to, and in some cases beyond, what people experienced at a much tenderer age. And when it comes to weight loss, although many styles of yoga will calm down and slow the practitioner’s metabolism during the time that he or she is doing yoga, the yoga will release PGC-1alpha. In the longer run, that induces mitochondrial proliferation. More mitochondria will convert more of what you eat into energy for your cells, accelerating fat metabolism.

TELOMERES

But there is still another way in which yoga helps with weight loss. In many instances, it actually turns back the clock. All creatures that are made up of more than one cell have strands of repetitive DNA protecting the precious DNA instructions that tell each cell what to be and what to do. Like bookends, these repetitive telomeres guard the special individual instruction-sets that make one egg a pigeon and another a trout. Each chromosome in each cell’s nucleus has strings of telomeric DNA at both ends that stabilize these critical instruction-lists analogously to the way a tail stabilizes a kite in the wind. Generally, within generous limits, the longer the tail, the more stability.

The telomeres steady your DNA within the silent biochemical maelstrom that constitutes life in a cell. These telomeres are generally shortened by each cell division, so older cells are less stable, leading to all kinds of dysfunctional behavior of the DNA—from decreased immune-system specificity to increased incidence of cancer, from reduced thyroid hormone output to poorer digestion. One major way, in fact the major way, we age is explained by the shortening of telomeres.¹¹

These telomeres appear to be the only aspect of inheritance that actually can be changed by what you do. The amount of stress in your life and how you handle it, what you eat, how active you are, and how happy you are may all affect telomere length, and may be passed on to your children. Your social support system, the trust you have in your friends and associates at work, even the neighborhood you live in can change the length of the telomeres in the DNA you pass on.

Although there are not yet any studies specifically targeting hatha yoga and telomeres, the practice of yoga, along with tai chi and qigong, has been shown to cut down on inflammation and oxidative stress—activities that are known to shorten telomeres. Further, meditation—whether in Jon Kabat-Zinn’s mindfulness, Deepak Chopra’s mantra-rich meditation retreats, or the more classical meditation generally practiced in the United States—actually increases telomerase, the enzyme that near-miraculously adds telomeres to your chromosomes.¹²

All of these practices have also been shown to shift gene expression away from stress and inflammatory reactions within cells. These effects reduce telomere loss and, in some cases, actually add to the telomeres on the DNA in the cell’s nucleus.¹³

There is another charming aspect of telomeres: You don’t have to fast for a week or complete arduous tasks of any kind to achieve lengthening. On the contrary, telomere length is increased by leisure activities, by lowering your stress, by doing things that make you happy.

In their book The Telomere Effect, Nobelist Elizabeth Blackburn and her colleague Elissa Epel define a person’s “healthspan” as the number of years that person’s cells are proliferating well, guided by longer strings of telomeres, and therefore consisting of essentially healthy tissues.¹⁴ “Diseasespan,” they write, is characterized by the years of illness and degeneration generally found in people at the far end of life. These authors argue extremely cogently that reduction in telomere length is one of the decisive factors in the transition from good health to chronic and terminal disease. When it comes to immune-system function, renewing your skin and the lining of your digestive tract, short-term memory, and even sexual prowess, telomere length is well correlated with youthful performance. The longer your telomeres, the more extensive your “healthspan.” Yes, longevity itself is actually also more or less proportional to telomere length.

Discovering telomerase, the near-magical molecule that promotes telomere growth, won Blackburn the Nobel Prize. It has been proved that telomerase can actually increase the number of telomeres dangling from the ends of chromosomes. What would you think might promote that? Generally, the answer is lower stress, a positive attitude, and, yes, physical activities such as yoga. It has been proved that people who respond to difficult situations with pessimism, hostility, or feelings of inadequacy have statistically significantly shorter telomeres. Those who are optimistic and confident, rising to the challenges of adversity, activate their telomerase and lengthen their telomeres, even in times of stress.

Meditation is a critical aspect, indeed the critical aspect, of yogic life. Even without a detailed discussion I can certainly say it is well-documented common sense that meditation yields a less anxious person, and lowering anxiety aids in the loss of weight.¹⁵ This has been proved at the biochemical level. As we have seen already, this applies to the metabolic machinery of every one of our billions of cells, to the tips of the chromosomes that foretell our longevity, and also at the feet-on-the-scale level.¹⁶

And now is a good time to summarize again the tangible ways yoga helps you lose weight. Neurophysiologically, yoga cuts down on your appetite by stretching the gastrointestinal tract, where receptors relay inhibitory signals to the appetite centers in the brain. And subtly, the foods that appeal to you may change; the apple may look more appetizing than the sausage.

Doing yoga helps you produce more burnable brown fat cells and cuts down on the more difficult-to-remove white fat cells. It induces your cells to have more mitochondria, increasing your overall metabolism.

And, as I must emphasize, yoga gives you calm, a way to reduce stress. This stress, the everyday kind you witness when a teacher is late for her class or traffic stops you from getting where you need to go, mobilizes hormones such as norepinephrine that actually accelerate oxidation in parts of cells, leading to degeneration. This is never desirable. But by providing the right sort of activity, yoga seems to promote and actually produce telomerase, improving your body’s function.