It seems like everyone is on Atkins, South Beach, or Weight Watchers. There’s a new gym on every corner, and a new weight-loss pill advertised during every commercial break. We’ve become a nation trying to shed our excess weight. And with good reason.

Approximately two-thirds of people in the United States are overweight (defined as having a body mass index, or BMI, of 25 of higher), and of those, almost half are obese (BMI of 30 or higher). A further substantial subgroup, defined as morbidly obese , has a BMI of 40 or higher.

Obesity is associated with an increased risk of type 2 diabetes , hyperlipidemia (elevated levels of cholesterol and triglycerides), hypertension , and obstructive sleep apnea , among other conditions. Not surprisingly, obesity can significantly decrease life expectancy.

But for those who are morbidly obese, diet and/or drug therapy alone do not usually lead to sufficient, sustained weight loss. In the early 1990s, the National Institutes of Health established guidelines for surgical weight loss therapy in patients with a BMI of 40 or higher, or with a BMI of 35-39 and related health problems such as type 2 diabetes or hypertension. Over the years, the medical literature has shown that this surgery, known as bariatric surgery , helps the extremely obese to lose substantial amounts of weight—often 100 pounds or more.

Now, in a meta-analysis published in the October 13, 2004 Journal of the American Medical Association , researchers showed that in addition to effective weight loss, bariatric surgery led to improvement or complete resolution of type 2 diabetes, hyperlipidemia, hypertension, and obstructive sleep apnea in a substantial majority of morbidly obese patients.

About the Study

Researchers analyzed data from 136 studies published between 1990 and 2003, involving 22,094 patients. For inclusion in the analysis, the studies had to enroll at least ten patients undergoing bariatric surgery, and had to report outcomes for diabetes, hyperlipidemia, hypertension, or obstructive sleep apnea.

The bariatric surgical procedures included in this study were grouped into the following categories: gastric banding, gastric bypass, gastroplasty, and biliopancreatic diversion.

Of the enrolled patients for whom this information was collected, 19% were men and 73% were women (8% did not report sex); the average age was 39 years; and the average BMI before surgery was 46.9.

The Findings

Weight loss was measured in terms of percentage of excess weight lost. In other words, the researchers first calculated the amount of weight each participant would need to lose in order to achieve an ideal weight. Then they measured what percentage of this amount the participants actually lost after their surgery. The researchers found that the average percentage of excess weight lost was significant for all categories:

Gastric banding, 47.5%

Gastric bypass, 61.6%

Gastroplasty, 68.2%

Biliopancreatic diversion, 70.1%

The average excess weight loss for all types of surgery was 61.2%.

Bariatric surgery was equally effective in treating obesity-related health problems. The procedure completely resolved type 2 diabetes in 77% of patients, and resolved or improved it in 86% of patients. For patients with hyperlipidemia, bariatric surgery improved the condition in 70% or more of patients. Hypertension was resolved in 62% of patients and was resolved or improved in 79% of patients. Finally, obstructive sleep apnea resolved in 86% of patients, and resolved or improved in 84% of patients.

How Does This Affect You?

This study clearly shows that bariatric surgery can lead to effective weight loss, as well as the resolution or improvement of some of the most common and serious obesity-related conditions in a majority of patients. Although the study could not directly address the effect of surgery on life expectancy, it's reasonable to assume that the resolution of these conditions will lead to a significant increase in longevity for these fortunate participants.

When considering a major medical procedure such as bariatric surgery, it is important to weigh the risks against the benefits. Morbidly obese patients must always endure a higher risk of surgical complications than non-obese patients. Bariatric surgery is no exception. And the long-term inconvenience of major, lifelong dietary restrictions is another important factor to consider before proceeding with surgery.

Clearly, bariatric surgery should not be seen as a silver bullet for someone looking to lose a quick 20 pounds. On the other hand, bariatric surgery may be an effective option for those whose weight might otherwise lead to early death. In this case, bariatric surgery is an option that may improve quality—and length—of life.