Weight loss and the case for Bariatric Surgery | The Body of Evidence

Weight loss and the case for Bariatric Surgery


In the conversation about weight loss, there's one technique we almost never mention even though it's very effective and is one of the few things that can actually prevent disease. That is bariatric surgery and it's the focus of my latest article for the Montreal Gazette.



When you start talking about weight loss, most people think about diet and exercise. But a recent survey in the United States found that people generally overestimate how effective diet and exercise are. The survey also found that people generally consider surgery, like gastric bypass, to be dangerous and ineffective. In fact, only a minority of patients eligible for gastric bypass are referred, reflecting a knowledge gap among both patients and their physicians about who would make an ideal candidate.

There are many different types of bariatric surgery procedures, but in general there are two main methods. In the first, a surgeon removes or bypasses a portion of the stomach to restrict its size as a food reservoir, thus getting people to eat less. In the second, a surgeon bypasses part of the small intestine, which leads to less absorption of calories. The reality may be more complex, and there is evidence that bariatric surgery also has an effect by suppressing hormones like ghrelin. To oversimplify, ghrelin is an orexigenic hormone that stimulates appetite and promotes weight gain. After bariatric surgery, ghrelin levels fall and no longer surge before mealtime, as they do in most people. So, bariatric surgery seems to help people not only lose weight, but keep it off by provoking hormonal and metabolic changes.

When successful, the weight loss can be dramatic. Seven years out, average weight loss can be over 80 pounds or 25-30 per cent of baseline weight. Contrast this with the five-10 pounds of weight loss seen in most diet studies. What is more, bariatric surgery has been shown to have multiple long-term health benefits. A recent study in JAMA surgery found that Type 2 diabetics who underwent bariatric surgery showed a 60 per cent remission rate of their diabetes that persisted seven years after their procedure. Another recent study in JAMA showed that bariatric surgery reversed and prevented high blood pressure.

Bariatric surgery is obviously not for people who want to lose a few pounds. The current indications are for people with a Body Mass Index over 40, or over 35 if they have an additional medical complication of obesity like diabetes, hypertension or sleep apnea. Candidates also need to be able to change their lifestyle, because not everyone benefits from surgery, and some of that variability can be explained by unhealthy eating habits. For example, bariatric surgery functions in part by curbing your appetite. But individuals who continue to eat despite being full or eating even if they are not hungry may not see any weight loss. Smoking, alcohol abuse and illicit drugs also seem to be negative predictors of success.

Bariatric surgery is a major procedure and not to be entered into lightly. However, its 30-day mortality rate is roughly 0.3 per cent and less than five per cent will have a major complication within 30 days of surgery, which makes it far less dangerous than most people generally assume. About one-two per cent of patients may require another operation, and with excessive weight loss, some patients opt for plastic surgery to remove skin folds. Bariatric surgery also requires long-term follow-up because malabsorption can also result in nutritional deficiencies if diet is not carefully monitored. Gallstones, ulcers, bloating, abdominal pain, diarrhea and hernias are well-described and sometimes common complications.

Clearly, bariatric surgery has complications, and as Kevin Hall recently put it, "we're not going to cut our way out of this obesity epidemic." But it is a potentially life-changing therapy that can prevent disease and decrease long-term mortality. We would be far better served as a society if we prevented obesity (especially child obesity) before it happened rather than treat it after the fact. But for people who have struggled with excessive weight gain, bariatric surgery is an important option that deserves more consideration.