Surgical Weight Loss: The Basics

Before we go any further, here, let’s be clear about a few things.  As we pointed out yesterday, bariatric surgery  may be a good option for an individual with severe – repeat, severe – obesity.  For such a person, it’s a very a big step to take and the actual surgical procedure is just one part of their ongoing weight control journey.  Long-term weight loss demands a commitment to changing the habits of a lifetime.  It’s not nip and tuck and on your merry way you go!  Nor is it a sure thing.

Research shows that many patients who undergo bariatric procedures regain some of that lost weight.  The amount regained varies according to the type of surgery and the severity of the obesity, but maintaining the loss is a daily challenge.  Old eating and snacking habits, old lifestyle habits, old routines and friendships – all these things and more have to be adjusted or left behind.  And there may be problems with the surgery itself.  It may not line up with the weight loss goals of some patients.  Separated stitches or a stretched pouch may affect the amount of weight lost.

Bariatric surgery leads to weight loss by restricting food intake.  The stomach can hold about 3 pints of food at one time.  As we eat, chewing and swallowing, our food moves down the esophagus to the stomach, where a powerful natural acid continues the digestive process begun in the mouth.  The stomach contents move on to the duodenum, the first part of the small intestine, where bile and pancreatic juice speed up digestion.   It is here that most of the iron and calcium in our diets is absorbed.  The rest of the small intestine absorbs most of the remaining nutrients and calories; whatever cannot  be digested passes to the large intestine, where it stays until eliminated.

There are four types of bariatric operations commonly performed in the US:

Adjustable Gastric Band (AGB).  The AGB works, for the most part, by decreasing food intake.  In this procedure, the surgeon places a small band around the top of the stomach in order to reduce the size of the opening from the throat to the stomach.  Inside that band is a circular balloon. The surgeon controls the size by inflating or deflating the balloon with a saline solution.  The size of the opening depends on the needs of the patient.  

Roux-en-Y Gastric Bypass (RYGB).  Here, food intake is restricted and how food is absorbed is also manipulated.  Actual food intake is limited as with AGB, while, at the same time, food is sent from the small pouch created by the procedure directly into the small intestine (hence the ‘by-pass’ in the name).  The stomach, duodenum and upper intestine no longer come into contact with food at all.

Biliopancreatic Diversion with a Duodenal Switch. Commonly referred to a the ‘duodenal switch’, the BPD-DS involves a complex, three-part process.    A large part of the stomach is removed.  The patient thereby feels fuller sooner.  The food is then re-directed away from much of the small intestine, limiting how the body absorbs that food.  Finally, there are changes in the way bile and other digestive juices affect the body’s ability to absorb calories and digest food, which  also leads to weight loss.

This BPD-DS is obviously a major undertaking.  When the surgeon removes most of the stomach, he or she creates a tubular ‘gastric sleeve’ which stays linked to a very short part of the duodenum, which is in turn linked to a lower portion of the small intestines.  Only a  tiny part of the duodenum, then, remains available to absorb food and a few vitamins and minerals.  The method produces very dramatic weight loss but, given the limited absorption situation, the likelihood of long-term problems is significant.  These problems include anemia and osteoporosis, among others.

Vertical Sleeve Gastrectomy (VSG).  Here again we have an approach that both decreases the amount of food absorbed for use and restricts actual food intake.  During VSG, most of the stomach is removed.  This may decrease ghrelin, a hormone that stimulate hunger.  It is thought that lower amounts of ghrelin may tame the pangs of hunger more than other restrictive surgeries, including AGB.  VSG was once performed as the first stage of the more extensive BPD-DS.  Interesting research has shown that some patients with VSG alone lose a lot of weight and don’t need the second procedure – an area still being studied.

Next up: more side effects, insurance options, research results.


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