Hey, Obese Americans: Sumo Wrestlers Say Eat Your Heart Out.

Like 60 million other Americans and a quarter of a million other Hawaiians, Fiamalu Penitani is obese. Severely so, in fact, with 520 pounds saddling a six-foot-four-inch frame. Fat all his life—in his Oahu high school, he was a 290-pound Greco-Roman wrestler and a nose guard for the football team—his girth quite literally gets in the way of many activities that smaller bodies take for granted. Flying is especially uncomfortable, for instance, because even spanning three seats, his back and hips get numb. Unlike the majority of other fat Americans, though, recent studies suggest there is little chance Penitani’s heart will ever succumb to disease or malfunction. He probably won’t die before his slimmer friends, either. So just what is it about this fat guy that gives him an edge in the fight against obesity-related health woes? Penitani—called Musashimaru in his professional life—was a grand champion sumo wrestler.  

In Japan—the land of painstakingly-pruned bonsai trees; where raw, lean fish prevails as the finest delicacy; where a popular hobby is the folding of paper squares into intricate birds and flowers; where the splendor of a geisha dance depends as much on the silks of her kimono as the lightness of her steps—the 1500-year-old, part-sport, part-religious ritual of sumo wrestling weighs in as the ultimate of cultural contradictions.  The Japanese are, by and (un)large, a lean people—the average man is 5’6” and just 143 pounds—and sumos, well, are not.

The rituals of a sumo match, too, are anything but dainty. Technically, a match is the one-on-one combat of two men, each trying to force the other to touch the ground or step outside an elevated clay ring. But as the typical brawl only lasts about 30 seconds, the charade that precedes it is the more fascinating element of the sport. The two loinclothed opponents start with elaborate gestures meant to intimidate each other. They slap their thighs, lift, flaunt and stomp the ox-like muscles in each of their tree-trunk legs, glare, groan, and even throw pillars of salt at their rival.  And though over 70 distinct moves—some so acrobatic they require the nimbleness of a ballerina—are officially recognized by the Japanese Sumo Association, the top wrestlers use only two or three of the most basic. Musashimaru’s favorite, for instance, was the brute strength maneuver oshi-dashi: a frontal push to drive the opponent backward and out of the ring.

Japanese sumo training begins as early as age 15, when the boy (and only boys, for the Shinto tradition purports that women and their “impure” menstrual cycles would contaminate the sumo ring) moves into one of 54 “stable houses” to train under a prominent master.  For the next few years in this spartan setting, the young hopefuls learn complex rituals and endure extreme physical training. Eric Gasper, an American who trained as a young wrestler in the early nineties, described the experience—where students may sleep 20 to a room, share squat toilets, and do their own cooking and cleaning—as “boot camp, prison, and war…all at the same time.”  On a typical day, the students wake at 4:30 a.m. and immediately begin a four-hour session of strength training.

Because there are no weight classes in sumo, the largest wrestlers have a major competitive advantage. But with such intense exercise, how do they put on so much weight? They eat—a lot. After the morning workout, wrestlers feast on chanko-nabe, a protein-rich meal-in-a-pot. There are dozens of variations of this hearty stew; typical ingredients include any combination of miso, beef broth, tofu, white rice, noodles, fish, pork, chicken, fried eggs, and fried root vegetables. And of course, the athletes wash down the enormous quantities of nabe with comparable amounts of beer and saki. But the real secret to weight gain comes right after the meal. Musashimaru, when once asked how he grew from 290 to 520 pounds, explained that sumos sleep immediately after eating, to insure slow digestion of their food and maximum retention of muscle mass.

A recent study from the Annals of Internal Medicine suggests yet another key element in the relationship between the sumos’ eating and sleeping schedules: hormones. Scientists have long known that the hormones ghrelin and leptin influence appetite; ghrelin secretion in the gastrointestinal tract stimulates appetite, while leptin production in fat cells represses it. But just last year, researchers at the University of Chicago published a further connection between these chemicals and the sleep cycle. The experiment subjected 12 healthy men to two days of sleep deprivation followed by two days of extended sleep, all the while monitoring their hormone levels, appetite, and activity. When sleep was restricted, ghrelin levels increased, leptin levels decreased, and consequently, the men’s appetites went through the roof. Their cravings for high-calorie foods increased by 45%. This hormonal play could thus explain the insatiable appetites of sumos—who get just six hours of sleep over the course of a typical day.

In November 2003, Musashimaru retired after a brilliant sumo career. In just 14 years, he became the first sumo wrestler in history to win 55 consecutive tournaments, and the second American fighter to achieve the most coveted rank of yokosuna, or grand champion.

Perhaps the only thing more surprising than Musashimaru’s rapid climb to the top of the sumo rankings is that his heart’s still ticking. For most obese people, their excessive weight, retained over months and years, steadily weakens their heart muscle. This makes obesity a major risk factor for all kinds of cardiovascular problems, including high blood pressure and fatal heart attacks. But for reasons just beginning to be understood by cardiologists all over the world, the hearts of sumo wrestlers are largely immune to these ailments.

Sumo wrestlers are physiologically different from the average obese Joe in two ways. First, their weight is made of mostly muscle instead of fat. Musashimaru’s body fat percentage at his heaviest, for instance, was around 20%. Compare that to the typical 500-pound man with a 70” waist (if, indeed, one can fathom a “typical” man of this enormity), whose body fat is about 35% of his weight.

Sumos also differ from other obese people in the way their hearts can handle the extra strain from their weight. Though the giants are some of the largest men in the world, the shape and function of their hearts is indistinguishable from those of the leanest of athletes.

Professional athletes are frequently diagnosed with a medical condition known as athletic heart syndrome. Characterized by an abnormally stretched heart muscle, the condition is basically the body’s way of adapting to strenuous physical activity. For a bigger heart means that a larger amount of blood (called stroke volume) can be pumped, and thus oxygen can be delivered faster to strained muscles and organs throughout the body.  But it seems that the phenomenon is not limited to lean athletes. A 2003 study published in the American Journal of Cardiology measured the heart size of 331 Japanese professional sumo wrestlers and found that just over 85% exhibited the ventricle dimensions of an athletic heart. This was surprising to the researchers, because the “static,” or non-cardio exercise done by sumos was not previously thought to strengthen the heart as much as that of, say, a marathon runner.

After the press conference where he announced his retirement, Musashimaru was quoted in multiple international newspapers mostly for just one phrase: “sumo hurts.” But apparently the pressure, harassment, and physical training required for excellence in the sport bring supersized health payoffs. And as anyone who has sampled it will tell you—tourists, internationally-acclaimed food critics, and especially the wrestlers themselves—chanko-nabe is delicious.