Joey Chestnut was in the zone, experiencing a competitive performance of a lifetime. Even when he was just a minute away from breaking his own world record, and most likely in severe discomfort, his face didn’t show any signs of stress. That’s probably because his cheeks were bulging like a chipmunk, as his mouth was filled with partially chewed hot dogs. In just 10 minutes, Chestnut consumed 75 franks. While it would take most people 10 days to consume 22,000 calories, Chestnut did it in the time it would take you or me stand in line and order a dog at a baseball game. As a sports scientist who studies the extremes of human performance, I’ve long wondered what the limits are to just how much a human being can actually eat in one sitting.

Discovering the boundaries of human gluttony was never part of my career plan. My research line has included an eclectic mix of topics related to human health, ranging from the health benefits of red wine antioxidants to improving the quality of sports concussion research. As a former competitive distance runner, I also have invested plenty of intellectual energy into the science of running, including how aging affects marathon performance in elite and average individuals.

Within the exercise physiology community, a popular topic of conversation has been whether or not a whether or not a sub-two-hour marathon was possible. (in late 2019, this was this was definitively answered in the affirmative by Eliud Kipchoge). As I read all of the literature attempting to predict the biological limits of human running speed, it dawned on me that the pattern of the world record progress in athletics also seemed applicable to the Nathan’s Famous Coney Island Hot Dog Eating Competition.

In the late 1990s, my father and I stumbled on a television program showcasing various competitive eaters, which highlighted the flagship Nathan’s competition. From then on, I followed the annual event, curious to see just how many hot dogs (with buns) a person could swallow in quick succession. When I first tuned into the contest, some men were eating more than 20 hot dogs in just 10 or 12 minutes—significantly more than the 10–15 it took to to win in the 1980s. By the end of the 1990s, the contest was attracting international attention, with Japanese contestants claiming the prized “Yellow Belt” in 1997, 1998 and 2000.

But everything suddenly changed when Takeru Kobayashi arrived on the scene in 2001, and stunned contest officials as he literally doubled the existing record by consuming 50 hot dogs. Kobayshi dominated for years, until Joey Chestnut dethroned the legendary eater when he consumed 66 hot dogs in 2007. In the 13 years since, Chestnut has been able to eat more and more, but his record has progressed only incrementally, reaching 75 franks in the 2020 contest.

This sort of world-record progression is not uncommon in running. In a sport’s early history, record performances are relatively stable with only moderate improvement over the years or decades. As sport participation increases, however and there are greater incentives for winning (such as prize money), competitors often come up with superior training methods and competitive strategies to maximize their chances of victory (sometimes adopting advanced technology or performance-enhancing drugs, which results in a rapid rise in world records). Eventually, the progression of world-record performances levels out again as all of the top competitors employ techniques known to be effective in their quest for glory. Indeed, this general pattern has occurred in human running, horse racing and greyhound racing. I simply borrowed the mathematical modeling techniques from these sports and confirmed that it holds true in competitive eating, based on 39 years of historical data from the Nathan’s tradition.

My analysis, published in the journal Biology Letters, revealed the somewhat shocking finding that world records in hot-dog eating are arguably more impressive than those in any other sport. Over the past 100 years, the world record for marathon running has increased by about 45 percent. While the sub-two-hour marathon was celebrated as a remarkable feat of human physiology, the average finishing time in a marathon is just over four hours—which means the best marathoner in world history is about twice as fast as the average healthy person. Even if you didn’t train, and just walked the 26.2-mile distance, you could cross the finish line in about 8.5 hours—about four times slower than a best-of-the-best champion marathoner. Yet Joey Chestnut’s record-setting 75 hot dogs represents a nearly 700 percent improvement in the world record over just four decades, and is at least eight or 10 times what the average person can eat.

Defining the “sigmoidal” pattern and magnitude of record progression was as far as my sports science background alone could take me. To understand how these seemingly ordinary humans could achieve such astonishing feats of eating led me down a new path that involved evolutionary biology and gastroenterology. My research revealed that top eaters like Chestnut are able to eat almost as much as a bear: around 800 grams of meat per minute, or about eight hot dogs every 60 seconds. When you take body size into account, however, the best human eaters actually far outperform bears. These comparisons aren’t exact (as the material properties of highly processed hot dogs differ from those of raw meat) but nonetheless provide some insight into just how impressive our eating capacity can be.

There is very little research on the competitive eating population, but examining data from binge-eating individuals, including obese and bulimic populations, provides some insight into how people can consume so much food. These patients, who consume large quantities quickly, are known to have a greater stomach volume than average, along with altered gastrointestinal function—the latter including the fact that their stomachs empty more slowly and have impaired satiety signals. One case study on a competitive eater revealed a similar effect after eating more than 30 hot dogs. Though there may be some natural variability in eating capacity, top competitive eaters do specifically train to achieve these gastric changes through quickly ingesting large quantities of food—especially liquids.

Indeed, my research revealed that a training effect seems to occur, as performance does improve significantly over an individual’s first five years of hot dog eating competition. Unlike other sports, where enhanced performance is only achieved by following a regiment that triggers a complex interplay of molecular signaling events in multiple tissues, it seems like eating capacity can be improved simply by stretching the stomach. This is a far simpler “adaptive” response than that of exercise training, and may explain the astronomical increases in world records. Perhaps studying these unique competitors can provide greater insight into how the gastrointestinal system works in both health and disease.

Ultimately, the mathematical modeling I performed suggests that Joey Chestnut’s record-setting 75 hot dogs in 10 minutes is not the pinnacle of what is biological possible. The historical data suggest that the record may eventually be able to rise as high as 83–84 hot dogs. My guess is that it will be decades before anybody approaches this, and it will take an individual taller and leaner than Chestnut to achieve this.

As the Major League Baseball season resumes in the midst of the COVID-19 pandemic, Americans will be eating more franks and celebrating the “dog days” of summer. For some of us, a single hot dog is enough to fill our junk food quota, while others may want to down four or more wieners before deciding they’ll have to pass on dessert. Regardless, next time we feel that we’ve overdone it with a gut-busting meal, we should take a moment just to reflect upon what it truly means to feel “full” and appreciate the human body’s amazing adaptability.