My favorite part of the marathon is carbo-loading the night before (which also marks the start of the Snackathon -- perhaps the only place where these two events dovetail). We chose Tony's, a family-style Italian place on Second Avenue, for our pasta feast. As I listened to five runners complain of shin splints, Achilles tendonitis and iliotibial band friction syndrome, it occurred to me that, were they all horses, I'd have to take them out behind the barn and shoot them.

"I'm the only healthy person at this table," I blurted. For at that time, only I could have stood up and walked around the block without pain. Each of these runners (and, I suspect, nearly every participant in the marathon) had suffered a training injury in the past six weeks. And each planned to run anyway.

That night, my wife spent about two hours valiantly coughing up phlegm. In addition to her hip injury, she was running with chest congestion.

On race day, I took Ellen to the bus at 6:30 a.m. for an early deportation to Staten Island. This gave me 90 minutes to make myself breakfast prior to my own ridiculously early departure (the whole city closes down by 9:00 a.m. on marathon Sunday), and I knew I'd need a big one. I fueled myself with bacon and eggs, and at 8:00 a.m., my friend Emily picked me up in her car. (It's a rare treat for a New Yorker to go anywhere by car.) As luck would have it, Emily goes to church in Bay Ridge, Brooklyn, every Sunday (her father is the minister) and I was allowed to come along for the ride. Luckier still, there are always good snacks at Emily's parents' house (they're Lutherans, thankfully, and not Episcopalians).

The scene at 86th and Fourth in Brooklyn, two hours before the start of the race, was pretty grim. It was me, a news crew, two cops and a drunk in a Yankees cap who kept yelling "Hang in daaaaauh!" Eventually, as hypothermia crept through my extremities, the Achilles Track Club runners started to pass (these are disabled runners who are allowed an early start). I desperately wanted a cup of coffee and a sausage McMuffin with egg (one of the cops had just turned me on to a nearby McDonald's), but I felt duty-bound to cheer the Achilles people. Somehow, their efforts seemed valiant -- as if they sought to prove, "I can be just as stupid with one leg as anybody with two."

Bringing up the rear were a few wheelchair-bound paralyzed competitors being pushed by able-bodied guides. To them I say, God bless you, for you are the only sane people in the race.

Just after 11:00 a.m., a small group of mostly Africans ran past like the wind, chasing a guy dressed in blue and yellow. The lead guy, a Mexican runner named German Silva who has won the marathon twice, had recently undergone a wart-removal procedure and didn't plan to race, so he agreed to act as the "rabbit." The rabbit runs as fast as he can for the first few miles of the race, and the others chase him, like greyhounds at a dog track. Silva chose to run past his designated jumping-off point, and had everybody scared for a couple of miles, but he eventually gave up and rode the rest of the way on a camera truck.

A couple of minutes later, a second group of Africans and Mexicans ran by. These were the female front-runners. Apparently they didn't get a rabbit because there were no women fast enough to do it. This gives an unfair advantage to the men, the women say, because not only does the rabbit provide psychological motivation but also he creates a windscreen for the lead group (and on this blustery day, the runners needed it).

Then, after a seeming eternity, the other 30,000 runners came pouring off the bridge and onto Fourth Avenue as in a scene from "Braveheart," casting aside their warm-up clothes (some nice stuff, I might add, although none of it fit me) and smiling maniacally. I saw Jon and Ellen pass within a couple of minutes of one another, although that gap would widen. At long last, I dipped into McDonald's for my sausage McMuffin (with egg) and ate it while reading the abortion-clinic and laser-hemorrhoid-surgery ads on the R train as I crawled through Brooklyn in the hopes of catching both of my runners five miles farther down the course, near a falafel place on Atlantic Avenue in Brooklyn Heights (which, it turned out, despite being in an Arab neighborhood, makes lousy falafel).

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Marathoning, we are told by the NYRRC (and dozens of other fanatical pro-running organizations), is for everyone. But is the human body really intended to run 26.2 miles at a stretch?

"A marathon is definitely not for the average person," says Dr. Stephen Lynn, director of the St. Luke's-Roosevelt Hospital Emergency Department, who has worked in the medical tent at the New York City Marathon finish line for the past 15 years. "I can't imagine how or why people do this."

Many obsessive runners are victims of either exercise addiction or fitness (aka non-purging) bulimia. Exercise addiction is a phenomenon thought to be caused by the release of endorphins (the body's version of opium) during exercise. Richard Benyo, author of "The Exercise Fix" and perhaps the foremost authority on exercise addiction, says you're an addict when "the obsession with your running turns to an arrogance of mind over matter, where you confuse willfulness to overcome your body's physical limitations with being strong-willed." Sounds like most marathoners I've met.

Fitness bulimia, by contrast, is really an eating disorder. As described by Dr. Jerald Block of the New York State Psychiatric Institute, it's the compulsion, in the wake of binge eating, to exercise excessively to burn every calorie ingested. It's analogous to vomiting or laxative abuse, albeit far less visually offensive.

I submit that both sets of people -- the exercise addicts and the fitness bulimics (and of course you can be both) -- are crazy. Yet society indulges them. As a fat guy, if I require medical treatment for obesity-related illness, I'm considered a drain on society's resources -- a lazy slob dragging down the nation's medical economy. But if I injure myself through overuse of my body, I'm heroic. Obesity, the propensity to eat (as nature intended us to do), is seen as a disease. Yet destroying oneself through exercise is considered virtuous, even though the costs of easily preventable orthopedic surgery, physical therapy and chiropractic care (which insurance companies in many states are now required by law to support) are immense (though undocumented by a medical establishment blind to the harms of overexertion). The entire discipline of sports medicine owes its very existence to people's voluntary abuse of their bodies.

Although I now lead a blissfully sedentary life, I'm intimately familiar with the fitness spiral. When I attended the University of Vermont, which is one of those colleges where everybody loves the outdoors, I fell under the influence of a friend, a bicycling and extreme-sports fanatic (and philosophy major) named James (who was later killed in a kayaking accident). Under his careful tutelage, I became a fairly skilled cyclist. I got to the point where I could spontaneously ride 100 miles (a "century") on any given day with no additional training. I got grouchy on days when I couldn't ride (which, given the Vermont winters, were many) and I spent larger and larger sums of money on better and better bicycles.

When I moved back to New York, where open roads are few, that regimen became untenable and I slowly detoxed from cycling, picking up squash instead. Never a good player, I nonetheless managed to injure myself in many dramatic ways before I gave it up. Now, I limit myself to walking and, on occasion (and only when I'm goaded into it), playing sports with friends for fun. I feel much better.

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The gap between my wife and brother-in-law (he's the faster of the two, and had fewer injuries) was growing, so Atlantic Avenue would be the last place I could see both of them. After cheering with what little voice I had left, I turned toward the No. 4 train station and braced myself for the Manhattan leg of the journey.

And it was then that I saw him. I never learned his name, but he was tall and blond. Just before Atlantic Avenue, he got a pained look on his face, departed the racecourse and ran down a street and into an alley. He emerged, missing a sleeve. He winked at me as he returned to the race. "Much better," said the tall blond man with one brown sleeve as he ran off.

Back in Manhattan, I barely had time to make it to First Avenue, where my mother-in-law was watching on 80th Street. As I approached over a small rise, I heard primal chanting and kept expecting to see Indians coming over the hill. I had missed Jon -- he was too fast for my snacking schedule -- but I arrived just in time to eat a feather-light cappuccino-flavored macaroon that my mother-in-law had bought at La Maison du Chocolat and cheer Ellen at mile 18. I then made a beeline for the 90th Street entrance to Central Park, approximately mile 23, the last place I'd be able to see my wife run.

On the way, I was lucky enough to pass the Papaya King hot dog stand on 86th and Third, where I purchased one with mustard and sauerkraut. While overpriced at $1.39, it was quite tasty and easily portable. I also picked up a Snickers bar at a newsstand. This was all along my beeline.

You're supposed to bring snacks for the runners, so I had a Zip-Loc bag full of orange slices that had been leaking in my pocket all day. At mile 23, I held out a few slices in my hand and, lo and behold, some passing runners grabbed them and ate them. So I gave away some more, and I felt I was doing a public service. Then, all of a sudden, one guy (his name was "Go Russell Go," according to his shirt) yanked the Snickers bar out of my other hand, mistakenly assuming it was for him, and ate it as he ran off. Luckily, I had a bag of potato chips as a backup.

The guy who stole my Snickers bar was no idiot. He understood about deriving pleasure from food. To the rest of the runners, who consumed thousands of packets of an evil substance called PowerGel, ingestion of nutrients had been reduced to its bare essentials: little colored gels with all the essential nutrients and no taste. This is food without enjoyment. Without chewing, even; it's the closest thing to intravenous feeding you can get without sticking a needle in your arm. It made me want to yell, "Soylent green is people!"

While watching the pained looks on the runners' faces at mile 23, it struck me: These people are not happy. They're driven not by pleasure, but rather by pain. Indeed, the only happy people were the spectators, and they were not as I would have imagined. I had assumed the marathon crowd would consist of fat people watching thin runners. But it turned out to be average people watching average runners. Many runners were obese or out of shape -- the marathon may have been their only serious physical activity of the year (and, according to the latest AMA study, people who embark on massive exercise programs with little pre-training have a heightened risk of heart attacks). Many of the female spectators were beautiful, healthy and rosy-cheeked, like cheerleaders in sweaters. Most of the female runners were anorexic and unappealing.

And I saw the guy with one sleeve, now just ahead of my wife and well on his way to a respectable 4:20 finish, although by now he was missing both sleeves.

When I saw Ellen, I was so elated that she had made it to mile 23 that, in an inexplicable paroxysm of poor judgment, I started to run parallel to her along a nearby footpath. After four blocks running and cheering, I was exhausted (in my defense, I was carrying a bag of clothes and snacks).

On the M96 cross-town bus, I caught my breath and amused myself by copy editing the MTA's near-illiterate public service posters.

The scene at the finish line was a gruesome one: 30,000 bodies, throttled to within inches of their lives, staggering aimlessly or lying on the ground, cramped and, in some cases, vomiting. The collective body odor was overwhelming, and a few European runners lit cigarettes. They had been running all day, and they looked terrible. I had been snacking all day, and I felt great.

This year, 55 runners were treated by the Emergency Medical Service on race day and hundreds more received unrecorded attention in the finish-line medical tents (and, of course, there are no statistics on runners who discover injuries in the days or weeks following the race). As far as I know, at last month's New York Wine Experience (an annual three-day oenological and culinary marathon, where more than 250 of the world's top winemakers display their finest at endless tastings and banquets), the only injury was a sprained ankle sustained when a waiter, carrying too much champagne, fell down the stairs.

The mother lode of snacks was at my mother's apartment, where the survivors assembled after the race. My mother had prepared her famous apple and custard pie, as well as a host of other favorites from my childhood (no stuffed cabbage, unfortunately). Later, we ordered Chinese food from Empire Szechuan across the street. My runners -- "Shapiro E., 30, Female, 4:39:04, No. 20,050" and "Shapiro, J., 33, Male, 3:30:20, No. 3463" -- had, on account of their injuries, both finished about 30 minutes behind their previous best times and would spend most of the next week recovering from the race.

But there was a happy ending for the returning heroes, as well as for all those who finished the marathon: This was perhaps the only day of the year when they could eat whatever they wanted without guilt.