Weight Loss Surgery Education

We feel it is important for you to have all the information you need to understand and make your best choice in bariatric surgery.  You may decide that surgery is not for you.  Our goal is to earn the right to have your confidence in this very important personal matter and to  that end we want to help you make the correct choice.  We are trying to make this information easy for you to understand.  Please realize we cannot tell you everything here.  To tell you everything we would have to write a book.  Wait a minute…Dr. Simpson already has written a book!  If you have any questions, please don’t hesitate to contact us.

Before weight loss surgery

Before getting into the thick of things it is probably a good idea that you understand a little about normal digestion.

The beginning…Normal digestion

Digestive system – stomach – before weight loss surgery

Digestion takes place when bile and pancreatic juice (coming from A and B) mix with food in the duodenum after leaving the stomach through the pylorus (C).

The food in the stomach is expelled into the duodenum through the pylorus, also known as “the holy pylorus.” The stomach’s job is to mix things, allow the acid to break them down, and begin the process of digestion.  Once the material has a certain consistency it is allowed to make the journey through the pylorus.  The pylorus, labeled “C”, is a sphincter that allows liquids and small particles of food through, but not large particles and not dense solutions (they have to be diluted a bit).

Leaving the pylorus, the food enters the duodenum—one of my favorite places in the body. Into the duodenum comes bile—which is made by the liver.  Bile assists in the breakdown of fat.  Bile empties into the duodenum (the bile duct is labeled A) two to three inches from the sphincter (labeled C).  The gallbladder is simply a storage unit for bile, if you don’t have the gallbladder your liver simply makes more bile—people live quite well without the gallbladder.

The pancreas also empties juices into the duodenum (the pancreatic duct is labeled B).  The pancreas makes a lot of fluid that helps to neutralize the acid of the stomach. If the acid of the stomach isn’t neutralized, an ulcer might result.  The most common place for an ulcer is in the area just after the pylorus—which makes sense.  The acid first hits here and the pancreatic juice to neutralize it comes in a couple of inches later.  The pancreas also secretes powerful enzymes to help break down protein.  So when the contents of the stomach mix with the contents of the duodenum, there is more digestion of food.  All through the bowel these digestive juices work to breakdown food into smaller and smaller particles that can be absorbed in the small bowel.

Restrictive and Bypass surgery

Surgeons learned long ago that patients who had a part of their stomach removed, ate less, were satisfied with less, and lost weight.  This became the foundation of the first attempts at weight loss surgery.  From that came a number of attempts at bariatric surgery — the first “stomach staplings” were performed to restrict the amount patients could eat.  These attempts were all called “restrictive operations.”

All weight loss surgery have restriction as their basis.  No matter what bypass components that the surgery has, the primary reason that operations succeed or fail is restriction. Now restriction is a funny word, it implies that the operation restricts the amount you can eat — and if you eat more that bad things will happen (vomit).  But that is really the incorrect message.  What really happens is that the top part of the stomach has nerves that, when activated by a simple stretch, tell the brain that you are “full.”

Whether it is a long-limb RNY, a Duodenal Switch, or a standard RNY — the bypass is less important than being able to eat less and be satisfied with it.  When those operations “fail” it is always traced to the stomach being able to get too much food in it.

Bypass Surgery

Bypass weight loss surgery – common channel

All bypass operations separate the stomach contents from the bile and pancreatic juice.

Where the stomach contents rejoin the duodenal juices is called the common channel.  The longer the common channel the more digestion occurs.

Bypassing or re-routing the intestines so you are unable to absorb food is an inefficient mechanism for weight loss, although it is spectacular to begin with.  One bariatric surgery that had only malabsorption as a weight loss component was the most popular weight loss operation in the 1970’s — but it was the most dangerous — it was called the jejunal-ileal bypass.  This operation left patients with great weight loss, but no component of restriction — so some felt it was wonderful — eat what you want and lose weight. The problem is that mother nature doesn’t work that way — and the resulting liver failure, kidney stones, and severe dehydration from diarrhea was such that the operation was discontinued in the United States for years.  The final problem with the operation is this: as with all operations– if people felt they could eat what they want and lose weight and don’t change their eating behavior, then they regain weight later.  In fact — for those patients who didn’t die from a purely malabsorptive procedure– the small bowel became better at absorbing food– and they regained their lost weight.  Today there is a thought that we can add Orlistat* to a restrictive procedure and have temporary improved results with restrictive procedures, but have a reversible malabsorption.  This, without re-routing intestines.  Interesting thought.

*Orlistat is a prescription drug that blocks some of the fat that you eat from being absorbed by your body.

The Lap-band and VBG are restrictive procedures…

…their sole mechanism is to restrict food intake—or portion control. They do not employ a surgical bypass alteration to the intestinal tract.

Purely restrictive (non-bypass) surgeries

Laparoscopic Band and Vertical Banded Gastroplastry are purely restrictive weight loss surgeries

Major types of surgery for weight loss


VBGLap-Band or other adjustable types of bandsRNY Fobi Pouch included in thisRNY-distalDS/BPD BPD without DS is rarely done in the United States
Restrictive or BypassRestrictiveRestrictiveRestrictive & BypassRestrictive & BypassRestrictive & Bypass
Percent of excess weight lost at five years 40-60%>75%50-75%60-75%>75%
Ranking for weight loss 4th? (1st or 2nd)3rd2nd1st
Vitamins neededYesRecommendedYesYesYes
B12 neededNoNoOftenOftenOften
Calcium neededRareRareRecommendedYesYes
Iron neededSometimesRareOftenOftenOften
Food restrictionsChew wellMinimalFiber may cause bezoars. Dumping may occur with high carbohydratesLow fiber, High proteinHigh incidence of lactose and wheat intolerance.  Fatty foods cause diarrhea
Downside of this operationHigh compliance needed for successRequires adjustmentsDumping, ulcer formation, strictures3-4 stools per day. Increased vitamin A, D, E, and K deficiency. Foul smelling flatus3-4 stools per day. Increased vitamin A, D, E, and K deficiency. Foul smelling flatus
Upside to this operationMinimal long-term nutritional problemsMost safe operation and as effective as othersBest studied of all operations, most commonly performedGood for patients with BMI over 50Fast initial weight loss

Frequently asked questions about Weight Loss Surgery

Can there be too much bypassed, or too short a common channel?

Yes. Most surgeons limit the common channel to 100 cm (40 inches). If you have a shorter channel you can develop protein-calorie malnutrition.  Some patients benefit from shorter channels, but the concern is always that they may not absorb enough protein.  Again, this is the choice of the surgeon.

Can there be too much malabsorption?

Yes, which is why the common channel size is important. With a 100 cm common channel it is very rare to have a patient become malnourished.

Can the common channel lengthen with time?

Yes.  The body does a great job of “accommodating” for shorter lengths of bowel.  When re-operating on patients, surgeons often note that the common channel has lengthened.  In fact, over time the effect of malabsorption is lost completely — and if patients have relied on the bypass segment without changing their eating habits, they will regain their weight.

If the common channel gets longer, can that contribute to regaining weight?

Yes. But typically the common channel should become better at absorbing things as time goes on.  Most people regain weight not from the common channel getting longer, but from the stomach (or pouch) increasing in size and patients eating more carbohydrates.

With a distal procedure, I heard I can eat whatever I want and not gain weight. Is this true?

There are always patients who claim they can eat whatever they want and still maintain a normal weight.  They cannot.  There is no surgery that will allow that.  Bariatric surgery should be the start of a change in lifestyle, including eating habits.  If eating habits are not changed, weight regain will occur.

Why can’t I have just a malabsorptive procedure?

The jejunal-ileal bypass was just that.  There was no limitation with the stomach.  Many patients thought this was ideal, as they could lose weight and eat what they wanted—or so they thought.  Over time these patients regained weight. Restricting intake is an essential part of weight loss surgeries, and one of the most important building blocks of all Bariatric surgeries.

What is the main cause of weight regain from weight loss surgeries?

The main cause is eating too many high glycemic index carbohydrates.  The most common finding of patients who have regained their weight is that the stomach size has increased (or pouch size).

How does the stomach (or pouch) get larger?

Typically this is done by constantly challenging it with increasing quantities of food. This is why we stress measuring your food before eating it.  The stomach does not become larger by over-eating at one simple meal.  Measuring twice and eating once is better than chronically over eating.

What are the advantages of the  Lap-Band over the bypass surgeries?

All adults should take a daily multiple vitamin, according to the National Academy of Science.  With bypass operations not only will you need  a multiple vitamin, you will also need supplemental iron, vitamins A, D, E, K, and Vitamin B12.  With the LAP BAND, you will only need a single multiple vitamin.  LAP-Band patients do NOT require protein supplements, additional calcium, or others.  Your guts are not re-arranged, there are no staples, and it is a safer surgery.

Can a proximal bypass be converted to a distal bypass and visa versa?

Yes, this can be done.  More often the proximal bypass is converted to a distal by pass when the patients are not losing enough weight.  But the common channel can be lengthened if patients are having severe malabsorption or problems with diarrhea.

How do I chose the right operation for me?

There is no magic formula.  Choose the operation that your surgeon does as a matter of routine.  Some insurance companies will only cover certain surgeons or certain operations.  They all work for weight loss.  Learn all you can about the operation you choose, learn how to live with that operation and how to make your new anatomy work for you.  If you are lucky enough to have a choice of surgeons and operations, then chose the operation that appears to work best with your lifestyle.  No matter which operation you have, you will eat differently after surgery than you do now.

Can the common channel be too short?

Yes. Not everyone is the same and a 100 cm common channel may not allow enough absorption of bile, protein, or foods, leading to protein malnutrition or severe diarrhea.  Some patients may need to have their common channels lengthened.

Couldn’t I just have a restrictive surgery and not have a malabsorptive component?

Yes.  The major source of weight loss for all surgeries is the restrictive component.  The restrictive surgeries are the most safe, do not require supplemental minerals, and they allow the entire GI system to be examined with an endoscope.

What will prevent me from shrinking to nothing?

The stomach, or the pouch, does enlarge with time and you will be able to take in more calories.  We expect this and want it to happen. Early on you will not be able to eat much, but as time goes on you will be able to eat more.  Use this “golden time” to make good food choices.