MODERATOR:
How does gastric bypass actually reduce appetite?

SCHAUER:
You know we're just beginning to understand the regulation of appetite. Appetite, meaning the desire to eat, is as complex as many other human urges we have.

We do know that there is much communication between stomach and intestines and the brain through various pathways. These can be hormonal as well as neurological. We haven't quite figured out exactly how these operations work in terms of reducing appetite, but we do know they are quite effective.

Some ideas put forth would suggest that filling the small stomach pouch stretches the small stomach, which sends signals back to the brain, telling the individual that they're full and satisfied. We call that satiety.

So we don't know exactly how these operations work. But if you ask any patient who has had gastric bypass, particularly in that first year, they will certainly tell you their appetite is much less, and they will tell you that a much smaller quantity of food fills them up and makes them feel satisfied. And that's the key. Many diets result in weight loss but still leave the individual wanting more. These operations are fundamentally different because they satisfy a patient's desires.

MODERATOR:
About the lap band: Why would you want to adjust the size of the pouch?

SCHAUER:
The advantage to the lap band is that the physicians can adjust the diameter so that it's just right. If the band is made too tight, then patients will have trouble getting any food down. They may have nausea and vomiting. A previous version of gastric banding had a fixed band that would not allow adjusting, meaning the surgeon had to guess the exact diameter that worked best for that patient.

A band can also be too loose, then anything flows through it and patients have very minimal weight loss, if any. A lap band's adjustability allows the physician, after the operation, to find the -- and pardon this pun -- the sweet spot that provides the best diameter of the opening to create weight loss but not cause undesirable side effects.

MODERATOR:
Given this adjustability, why is the lap band produce less common than the gastric bypass?

SCHAUER:
A good way to look at this, Kate, is that the band has part of the components of the bypass. It has the small stomach component, the pouch, but doesn't have the bypass. So the band is two-thirds as effective as the bypass because it has just the restrictive component of the operation and not the bypass component.

MODERATOR:
What would happen if you used the restrictive component of a lap band with the bypass portion of the gastric bypass?

SCHAUER:
These two operations have not commonly been used in combination. However, there are some surgeons beginning to combine them in more of an investigational manner. Right now they are not available in wide use together, but in the future that may be a possibility.

MEMBER QUESTION:
Do you create the same size pouch for everyone during surgery? I have heard of people having a larger pouch than others and they end up gaining their weight back.

SCHAUER:
Regarding pouch size, most surgeons try to make the pouch as small as possible for that very reason. A large pouch overtime has a tendency to stretch and patients will consume more food to reach that point of being satisfied.

So most surgeons do advocate or create a relatively small pouch -- again, the size of a walnut or in medical terms, approximately 15 milliliters in volume. In general, the smaller the better.

MODERATOR:
What happens if someone has the procedure and does overeat with this small pouch?

SCHAUER:
While overeating may happen within the first few months of surgery, it's quite uncommon after because, again, patients become accustomed to their smaller stomach and their overall desire to eat a large meal is decreased, and they begin to have a strong sense of when they are full, and so they stop eating.

Nausea and vomiting may occur perhaps in the first few months. It's rarely a significant issue. I must say that after six to nine months after surgery, it is quite rare for patients to overeat.

MODERATOR:
So the surgery is not a license to eat.

SCHAUER:
Correct. These two operations cause weight loss principally because fewer calories are consumed in the body. Now, having said that, there's another operation which I didn't talk much about, that's less commonly used in the United States -- less than 5% of the operations.

It's called mal-absorption procedure. Unlike the gastric bypass, it involves bypassing most of the intestines so that only a small quantity of calories can be absorbed by the body. So these patients have a much larger stomach and consume quite a large quantity of calories, perhaps even more than 3,000 calories a day, and still lose weight because only a small quantity is absorbed. These mal-absorption operations are very effective.

However, these operations have a much higher rate of nutritional deficiencies. These patients often have diarrhea or many loose bowel movements per day, and they may have nutritional deficiencies such as anemia, fat soluble vitamin deficiencies, and protein malnutrition. Some of these patients will require artificial nutritionthrough their veins for some period to replete their body of these important nutrients.