Dan Benintendi

Dan Benintendi (Brandon Thibodeaux, For the Chicago Tribune / April 26, 2012)

You could say that Dan Benintendi is hooked on exercise. On a typical morning in Fort Worth, Texas, he wakes up at 3:30 a.m. to swim 2,500 yards. Then he teaches a one-hour spin class, works most of the day as an AT&T account manager, teaches another spin class and heads home to his wife and three young kids.

As an ironman competitor who dabbles in marathons and 100-mile "ultra" runs, working out for three to four hours a day isn't so unusual. But those workouts are a far cry from the Benintendi workouts of four years ago.

Back then, he weighed 400 pounds and could barely muster the energy to get off his couch and go to work.

When his wife told him she felt like a single mom, doing everything around the house because he was too tired to help, Benintendi took action.

"It wasn't fair to her or the kids, so I decided to make a change," said Benintendi, 36, who at the time was stopping at drive-thrus to eat two meals before coming home for dinner.

His weight had seesawed before — he'd gained and lost hundreds of pounds — so losing weight wasn't the problem. "I could do that," he said. "The problem was keeping it off."

This time, Benintendi took the first step in that direction by undergoing gastric bypass surgery.

Shedding so much weight would take time, and maintaining the loss would involve reviving the athlete he once was. But his determination paid off when, nine months after surgery, Benintendi completed his first sprint triathlon at 250 pounds.

Safely reaching this goal required careful consideration of nourishing an altered body, and it presented a challenge most athletes don't have to grapple with — managing the excess skin remaining after extreme weight loss.

The procedure

Gastric bypass surgery involves reducing a person's stomach to an egg-sized pouch, said Benintendi's surgeon, Dr. David Kim. The pouch is connected to the lower part of the small intestine, skipping the upper part. The pouch holds much smaller amounts of food and liquids, and that limits the intake and absorption of calories, fat and vitamins. Patients have to take vitamin supplements to compensate. Iron stores are also depleted, and sugars aren't processed as well.

The road back

Surgery isn't a cure-all, of course. After the procedure, patients are urged to exercise at least 30 minutes, four to five days a week, to shed their extra weight, and they must change the way they eat.

Four or five weeks after the surgery, Benintendi got on a treadmill, set it at 2.5 miles per hour, and was winded within 10 minutes. He went back the next day and each day after that, adding one minute of exercise. The next week he increased the speed to 2.6 mph, and within three months, after slow and steady increases, he'd lost 100 pounds.

Then one morning he spotted an indoor cycling class and gave that a try; he lasted 30 minutes the first time but eventually made it through a whole class. After that, he added swimming to the mix, starting with a single lap and increasing the workout one lap at a time.

There's no reason that someone who's undergone gastric bypass and is otherwise healthy can't participate in endurance sports, Kim said. "The body is remarkably adaptive and, in time, it learns how to reabsorb calories and other nutrients in abundance as it had once before."

The typical gastric bypass patient will have lost up to 80 percent of his or her excess body weight at 18 months after surgery, Kim said. Some weight regain is common, and this drops to 65 percent of excess body weight at five years after surgery. According to Dr. Philip Schauer, a bariatric surgeon at the Cleveland Clinic, 5 to 10 percent of bariatric patients gain all their weight back. That's why bypass patients have to be invested in weight maintenance through diet and exercise, Kim said. Their bodies can find ways to gain back the weight they've worked to lose.

Unique challenges

A month after Benintendi finished his first sprint triathlon, he did another one. We're talking about an event comprising a 300-meter swim, 14-mile bike ride and 3.2-mile run. Then, "I started to think bigger," Benintendi said. "I thought, maybe I could do anything I want."

Eleven months after his surgery, he completed his first marathon in a respectable 4:52:00. He did another one a few months later. In 2009, he completed four half-ironmans (1.2-mile swim, 56-mile bike ride, 13.1-mile run), a full ironman and a few more marathons. (Benintendi said he knows of a dozen other gastric bypass ironman athletes.) In 2010, he attempted a 100-mile run and made it through mile 75, in 23 hours. He tried another, then finally completed one last year, running 104 miles in 28 hours.