Surgeons have been performing bariatric, or weight loss operations since the 1950s, but they're much safer than they used to be. They're typically done laparoscopically now, where doctors use tiny surgical tools and video cameras instead of making big, deep incisions.
Despite the increase in obesity, only a small number of people have had the gastric bypass operation.
Correspondent Lesley Stahl met some people who were once morbidly obese.
There was Tony Sideman, who underwent surgery in April 2007 and has lost 140 pounds; there was Janet Rovak, who lost 90 pounds in the eight months since her surgery; and there was Travis Goodbou, who lost 260 pounds in the seven months since he underwent the operation.
Dr. Neil Hutcher from Richmond, Va. has performed more than 3,000 bypass surgeries. Asked how many people gain the weight back, Dr. Hutcher tells Stahl, "You know I think when you're dealing with an incurable disease that kills many people, if you have an 85 to 90 percent success rate, that's pretty darn good."
"Is that what you have?" Stahl asks.
"Yeah," Hutcher says.
There's no diet, no exercise regimen, and no pill with a success rate like that. These patients lose a ton of weight and keep it off.
Here's how Hutcher does the surgery: first, he sections off a small pouch of the upper part of the stomach, which is then attached to a lower part of the small intestine, bypassing most of the stomach, so that there's not a lot of room for food.
It used to be that roughly one in 100 people died from this operation. Hutcher says it's now about one in 1,000, which makes it less deadly than most major surgeries.
"It's less than gall bladder surgery. It's about one-tenth of cardiac surgery," he explains.
It's safer because of new surgical techniques which have also made it more effective. For instance, they can make the stomach pouch smaller than they used to.
"Even if I wanted to eat a whole cheesecake, my stomach is very tiny. It holds four ounces max, stretched to the max. And that's not even one piece of cheesecake," a female patient explained.
A big reason the operation works is because it seems to suppress appetite. "If you listen to your patients, they come back and they say, 'Doctor, you put the fire out,'" Hutcher says.
"When you see a sign for fast food or…she's already shaking her head at me," Stahl asked a patient.
"Don't want it," the female patient replied. "I used to crave sweets all the time. I couldn't go past the gift shop at work without getting a candy bar. Now I go past it and I never give it a thought."
Paul Delios of Saugus, Mass. has lost 90 pounds. He owns a doughnut shop with his siblings, but he's able to resist the cravings. "Before I'd have cravings for everything. Now I really don't," he told Stahl.
For most patients the cravings really do disappear. One theory is that's because the operation suppresses the levels of a stomach hormone called "grelin" that activates the sensation of hunger.
Yet most people who have this operation do not get skinny. Dr. David Cummings, an expert on appetite at the University of Washington, says as a rule these patients end up just one third lighter.
"Most people with severe obesity who undergo gastric bypass do not become fully normal, in terms of body weight. They go from severely obese to mildly obese, or from obese to overweight. But nevertheless it's an enormous change," Dr. Cummings explains.
And not just in terms of weight loss. Dr. Hutcher says the operation itself can take type 2 diabetes - which has ballooned in this country - and throw it into complete remission.