A recent review of research on the physiology of the adjustable gastric band has shed some light for me on how to properly manage eating after this procedure and how to educate patients on proper eating for success after surgery. 

First, one of the keys to success after surgery is to be at an appropriate fill level.  To assess adequate fill levels in the band researchers in Australia developed the Green Zone Chart:

The goal after surgery is to get to and maintain residence in the green zone.  This means understanding when it is time to get a fill and when you are overfilled.  Your eating habits can also have an impact on what zone you are in, as you will see later. 

Dr. Paul Burton, a bariatric surgeon in Australia has done studies on the pressure provided by the band while patients were in the green zone.  It was found that each bite of food should completely cross the band before another bite is swallowed.  Food passes the band through esophageal peristalsis (contractions or waves of the muscles in the esophagus which force food to move).  The goal is that a small, single bite of food is chewed until it is mush.  Then through peristalsis it will move across the band, taking multiple squeezes (usually 2-6), in green zone adjusted patients.  In patients who are underfilled or overfilled it will take less or more waves to push the food past the band.  It was found that the squeezes of the esophagus are what cause the sensation of no longer being hungry and that each squeeze adds to the satiation signal. 

It is hypothesized that sensors called intraganglionic laminar endings (IGLEs) are responsible for the feelings of satiety.  IGLEs are known to detect tension within the wall of the stomach and may be responsible for recognizing the compression of the gastric wall associated with squeezing of the bite of food across the band.  Therefore, the several squeezes that allow for the transit of a bite may stimulate the IGLEs further.  The IGLEs in turn signal the hypothalamus (the part of the brain in charge of hunger control) and the urge to eat is decreased.  According to Burton, a properly adjusted band provides adequate resistance to flow and the well-chewed bite of food generates more signals and yields increased satiety on less food.  When one is not eating properly:  not chewing food thoroughly to mush, eating too quickly, or taking too large of bites, the segment of the esophagus which contracts can be stretched, resulting in a decrease in peristaltic power and ultimately causing a return of hunger.

The article also highlights the “Eight Golden Rules” of eating after placement of an adjustable gastric band.  I agree with these eight rules as they are also included in the initial recommendations we provide and are consistently reviewed at your follow up appointments:

1.  Eat three meals per day
2.  Do not eat anything between meals
3.  Eat slowly and stop when no longer hungry:  One should be taking small bites       
and chewing thoroughly.  Small utensils should be used.  Each bite should be chewed for at least 20 seconds to allow for food to be chewed to mush as well as allow for the tasting of food.  Once a bite is swallowed one should wait 1minute before taking another bite to allow for the 2-6 peristaltic waves it will require to completely force the food across the band.  A meal should not last more than 20 minutes, therefore, at one bite per minute it would consist of 20 SMALL bites and 40-120 peristaltic waves or satiety signals. The number of signals produced depends on the consistency of the food, the tightness of the band, and esophageal power.  It is enforced that eating should discontinue when one is no longer hungry as opposed to being full.  Eating to being full means that there is food above the band which can cause distension of the contractile portion of the esophagus which enables optimal eating behavior and appetite control.  
4.  Focus on nutritious foods:  one should consume a protein rich diet with high quality sides such as vegetables, fruits, and whole grains.   
5.  Avoid calorie-containing liquids:  Foods should be solid since liquids pass too quickly across the band and do not provide the peristaltic waves needed to induce satiety.  
6.  Exercise for at least 30 minutes each day
7.  Be active throughout each day
8.  Always keep in contact with us

Along with the “Eight Golden Rules” for eating there are eight words that you should constantly repeat to yourself as a reminder of how to eat properly after Lap-Band surgery “Eat a small amount of good food slowly.”

Weight loss failure after Lap-Band surgery can occur because the band is not placed correctly, the band is not adjusted properly, or the patient does not adhere to the guidelines of proper eating and exercise.  Out of these, the most common reason for weight loss failure is poor eating behavior which leads to esophageal enlargement above the band.  These poor eating behaviors include:

1.  Not chewing food adequately.  Food MUST be chewed to MUSH before swallowing.  If the food is of the texture that it can not be reduced to mush it should be spit out rather than swallowed.  
2.  Food is being eaten too quickly.  Time should be allowed for each bite to be completely squeezed across the band before another bite is taken.  One minute appears to be an appropriate amount of time to wait between swallowing one bite and placing another bite in your mouth.
3.  Bites are too large to pass through the band. 

When these behaviors occur, food builds up above the band where there is no space to accommodate it.  To make room for this food, enlargement of the lower portion of the esophagus occurs.  This inhibits the lower esophagus from squeezing properly which prevents it from generating the signals of satiety explained above.  Hunger continues, more food is eaten, more stretching occurs, etc. . .and weight is regained or simply never lost.  Chronic stretching yields vomiting, heartburn, and decreased ability to sense when one is no longer hungry.  Eventually, this can cause enlargement of the esophagus to a point where it may prolapse over the band, and the band will either need to be replaced or removed. 

As you can see it is very important for your weight loss and maintenance that you achieve and maintain your adequate fill level as well as follow the eating recommendations so that the Lap-Band will be able to do its job.  Remember that the band is only a TOOL.  You are the one that is making all the appropriate decisions which allow it to function properly. 

References:
O’Brien P.  Gastric Banding and the Fine Art of Eating.  Bariatric Times September 2011:  1, 18-21.