Roughly 300,000 people in the United States die prematurely each year as result of obesity, and more than $150 billion is spent on obesity-related health conditions. What can be done to stem the tide of chronic disease, death and red ink caused by this epidemic? John Sanford, a writer for Stanford Hospital & Clinics, spoke with John Morton, MD, MPH, one of the leading weight-loss surgeons in the country, to find out. Morton is director of bariatric surgery at Stanford Hospital and associate professor of surgery at the School of Medicine.

What happened to plain old diet and exercise?

Morton: Well, when it comes to a body-mass index over 30, which generally marks where obesity begins, it's very difficult to lose weight on your own. If you follow the studies — the longitudinal data — the evidence for this is pretty compelling. About 95 percent of patients do not lose weight without some kind of intervention. There are better treatment programs for crack cocaine than there are for morbid obesity, meaning a BMI over 39. Those are simply the facts.

It's important to remember that obesity is not caused by a lack of willpower. As anyone knows, it is hard to stick to a diet. If you look at the attrition rates of Weight Watchers participants, you'll see that everyone starts out at 100 percent adherence. After 10 weeks, however, only 40 percent are still with the program. At 50 weeks, only 10 percent are still sticking with it.

Why is it hard to stick to a diet?

Morton: There are many physiological barriers to losing weight. If you think about it from an evolutionary standpoint, maintaining your weight is pretty darn important. Look at the levels of ghrelin, the so-called hunger hormone, in a person who lost weight on a diet, and you'll see they are much higher than before. Levels of another hormone, leptin, which suppresses hunger and speeds up metabolism, are lower. Your body's not stupid. It knows you have lost weight and will do everything in its power to get that weight back. This is why you see the rebound effect — people gaining back their pre-diet weight and sometimes more.

How can weight-loss surgery help?

Morton: I like to say it gives people a hunger holiday. If you just look at ghrelin levels after gastric bypass surgery, you see they go down to almost zero. It allows patients a break from all the "head hunger" and anxiety about weight. You've heard doctors talk about the golden hour in trauma? Well, bariatric surgery gives patients a golden year in which they can take time to change their habits to sustain weight loss. And studies show that it's effective in the long term. After 10 years, a 2004 study showed that gastric bypass patients had lost almost a third of their weight. The study showed that patients who got gastric banding, in which a band is fitted around the upper part of the stomach to make a smaller pouch, lost about 15 percent of their weight over that time.

What is also impressive is the reduction of co-morbidities over time. You see big reductions in hypertension, hypercholesterolemia, sleep apnea and depression. The real eye-opener is the improvements to diabetes. A 2001 study showed an 82 percent resolution rate of diabetes in morbidly obese patients who underwent laparoscopic gastric bypass surgery. They were able to stop taking medications — no Metformin, no Actos, no insulin, no Byetta — and that happened very quickly. This is where bariatric surgery certainly can make a difference.

What about the value of weight-loss drugs and prevention?

Morton: Prevention obviously is a terrific idea. I look forward to everything that's going to happen there. And it's clearly been neglected for a long time, but it will take about 20 years before these efforts really take hold and begin to yield results. You end up losing a generation. What do you do for people right here, right now? So, prevention is terrific, but we're not going to see results around the corner anytime soon.

As for medications, want to venture a guess as to how many there are on the market today for obesity? Right now, it's one. It's called Alli, and it's not exactly a blockbuster drug. It works strictly by decreasing the amount of fat absorbed by the intestines. You lose a grand total of about 13 pounds at the end of a year. Three other drugs recently came up for approval, but they were all shot down by the FDA, which I think is very wary after its experience with fen-phen. [This anti-obesity drug, which was approved by the FDA but withdrawn from the market in 1997, was shown to sometimes cause pulmonary hypertension and heart-valve problems.]

How many people get weight-loss surgery?

Morton: Although roughly 15 million people in the United States are morbidly obese, only about 1 percent of those who were clinically eligible had bariatric surgery in 2009 — about 220,000 people. And the thing is, the surgery is cost-effective. A 2008 study on its economic impact estimated that the costs of laparoscopic weight-loss surgeries were recouped in two years by morbidly obese patients who had the operation. In other words, they got a complete return on investment in two years, based on not having to pay other medical costs incurred because of their weight. Patients who had open surgery, as opposed to laparoscopic surgery, recouped their costs in four years. Bariatric surgery is also now safer than it's ever been. The New England Journal of Medicine published findings in 2009 from the Longitudinal Assessment of Bariatric Surgery Consortium showing that the mortality rate for 2,975 morbidly obese patients 30 days after they got laparoscopic gastric bypass surgery was just 0.2 percent. Of 1,198 patients who got laparoscopic banding, the mortality rate at 30 days was zero. So the safety is good, especially compared to the risks of extreme obesity.