This was originally posted by Pickles123.  Her Dr. Terry Simpson wrote this article on how the band works.  It really explained a lot to me and aligns with what my surgeon says as well.  Pam W. asked me to repost it, so here it is!

I hope it helps clarify any questions you have about the role restriction does and/or doesn't play in life banded.

The Lap-band is NOT about Restriction

When talking about the band, some patients talk about restriction.  Let's first be clear about one thing: the purpose of the band is not restriction; the purpose of the band is to lose weight by suppressing the appetite.

When band professionals talk about restriction we  are talking about something totally different than "restricting what a person eats." In fact, many band surgeons avoid talking about restriction so as to not confuse patients.  The band works by dimming the appetite, and this provides a conscious control and decision made by the patient, it does not work by "making" a person do something, or keep them from eating too much. 

The Lap-band works by suppressing your appetite

As a result, you are less interested in food between meals, making it easier to resist temptation.  The analogy is when you are near a vending machine when you are hungry-- what do you do?  Probably find yourself with some  junk food that is not a part of your plan. But, when you pass a vending machine when you are full, it may not even catch your eye. Having the appetite dimmed makes you less tempted by the many food choices modern living throws at you - -this is what the band does, by suppressing appetite you become less interested in food.

What you should not feel, with the band, is the sensation of being "stuffed."

When you eat Thanksgiving dinner, you can feel stuffed.  Contrast that with the sensation two hours after you eat your big meal, at that point your appetite is suppressed.  It is the subtle dimming of the appetite that the band should provide.  Being stuffed after a large meal is a complicated sensation of the abdominal wall stretching and a lot of gas in the bowel, in addition to feeling a diminution of appetite. You will not, and should not, feel the abdominal wall stretch with the band.  You should not feel the "near nausea" and you should not feel bloated. 

Key point:

You should NEVER eat until you feel full. It is best to stop eating before you "feel full."  If you do eat until you feel full you will most likely be overstuffed.  This leads to the universal key to success -- patients who eat a small volume of food (which, if you measure, is consistent) will be successful with the band.  If you want to succeed, you need to know how much you are eating, and then stop eating -- it is in your control, but the band will help you -- not by stopping you, but by allowing you to feel satisfied after the small volume.

Early on, most Lap-band patients do have a sense of "restriction"

...particularly after the first fill. When we place the band on a patient the stomach above the band typically will hold one to two ounces (by volume, not by weight).  The stomach has a lot of muscle fibers, and the wall of the stomach is fairly thick.  When food is consumed, it arrives in the  pouch, and meets some resistance, first against the newly adjusted band, and then against the stomach which does not stretch easily.  People love this feeling!  It is a sense of control over food -- a leash. But it is not permanent. It makes it difficult to eat more, because the top part of the stomach and the band will resist it.  If you over eat you will feel uncomfortable.

This is the honeymoon phase, you feel full with less, no appetite, and if you try to eat more it doesn't work. They eat a small amount of food, they feel satisfied, and they are losing weight.

For patients *****ly on this sensation, they will find it will take ever increasing volumes of food to obtain this sensation. The initial response is to have their band adjusted so that they can "feel full again."  Against a tighter band, the upper stomach stretches a bit (and if they eat fast it stretches more)and they again have the sensation of "feeling full." This becomes a cycle, a tighter band, the stomach stretches more-- and then instead of going back to its original size, the stomach stretches more and more to where it takes more to fill it.

The person who continues to eat until they have this sensation, will find that it takes more and more food to obtain this feeling. Two things happen -- first the stomach stretches to where it accommodates more food, and to stretch it means you have to eat more. The second is that to "feel full" it takes the brain time to register this sensation -- this is not the sensation registered by the hypothalamus, but registered in the conscious cortex. So your stomach can be full, but your brain won't register it for a while, and if you keep eating you can overeat.  As a result, the pouch dilates.  Similar to a balloon, when you first start to blow up the balloon it takes a bit of force.  As you continue to fill the balloon, the wall of the balloon stretches (thins out), it is easier to blow it up -- the same is true with the upper pouch.  Early on, before the pouch is stretched, it takes a little bit of food  to cause it to stretch, but with chronic over-eating the pouch will accommodate more and more food. The stomach wall is thinner, it is easier to stretch, and to get that sensation it takes more food than at first. Often patients will complain that they "don't feel restriction," and wish to have the band made tighter.

There are two potential results to this: one is the patient will passively stretch the stomach and esophagus and not be eating a small amount of food.  These patients simply do not lose the weight that the surgeon expects. The other is that the band will be forced down the stomach, the band will slip, which generally requires operative intervention to reposition it.

For those patients who are rigorous about the volume of food they eat, and do not let the stomach to tell them when to stop eating - they do very well. This is one of the keys of successful patients, only eat a certain portion of food - period.   If the band is properly adjusted, the appetite will be dimmed for several hours.  Once your brain realizes that a small amount of food keeps you satisfied, then your eyes will adjust to the amount you eat.

Some describe a "soft stop." Where before a sense of fullness occurs, there is a signal from your body -- this can be a runny nose, a sigh, or a subtle ache in the left shoulder.  Patients who find this "soft stop," do very well with the band.

The other advantage of eating small portions is it becomes a lifestyle change

--you will have the ability to gauge the amount of food you can comfortably eat, knowing it will keep you satisfied for several hours.

You can always -- always, always, always, -- eat more food, because, contrary to what we believed for a long time-- food passes by the band within a minute  and then into your stomach. But the key to successful patients is not how much they can eat, but how little they can eat to suppress hunger.

The band goes around your stomach, not around your brain, or your lips

This simple concept, of eating a specific volume of food -- eating it slowly, and then walking away, is the key to successful eating habits of patients.  This means that the band works with effort from you -- not by it doing everything for you.  You have to make the decision to eat a small volume of food, and let the band work with you.

The sensation that we would want the band to produce is the "soft stop."  The soft stop is when you eat a small portion of food and walk away.  Sometimes this is difficult, like most things, practice makes perfect. To set yourself up for success -- we recommend you use smaller plates, along with smaller utensils.  If you go out to eat, ask for the to-go bag immediately, and remove the excess food from your plate.  You can physically always eat more food, but the advantage about practicing small portions and walking away, is ultimately your eyes will get use to what the stomach is telling it, and it will be much easier to eat smaller portions as time goes on.

It isn't uncommon for patients to want an adjustment because they say they can eat more

The first question we ask is, "Why are you eating more?"  The typical answer is, "Because I can." The typical response, "Just because you can does not mean you should."  Since the band's job is not to restrict the amount of food you eat, do not leave that to chance -- that is your job. Part of personal accountability is to account for, to measure, to know how much you are eating at a time. The band is empowering; if you eat an appropriate amount and make appropriate food choices, you will be satisfied for several hours. This results in either weight loss, or weight maintenance (if you are at your goal). The purpose of the band is to assist you to lose weight -- and this occurs only with active participation by you: you chose what to eat,  you choose how much to eat, and you practice walking away after eating that amount.  The band is a tool to allow you to eat less and have your appetite dimmed resulting in weight loss, or maintenance. It is a tool to help you adopt a healthy lifestyle -- you still have the choices to make, but the band allows you to be satisfied with those choices.

"If I could eat less and walk away, what would I need this band for?" -- a common question we are asked. Without the band, if you eat a small amount of food and walk away your appetite would rise within a couple of hours --  you would find yourself hungry and wanting more food, possibly leading to unwanted snacking. You would also find, if you willed yourself to withstand the hunger, that your weight loss gradually decreases.  The band fools your brain into thinking you ate more.

Think of it another way -- the hypothalamus does not have eyes -- it doesn't know how much you ate, it doesn't know if there is a lot of food around and you are not eating it, or if there is a band on your stomach.  The hypothalamus reacts very simply to the stimulation provided by the upper part of your stomach.  Stretch that thermostat, it thinks you are eating a lot -- do that consistently over time, and it behaves as if you are eating a lot all the time and will allow your body to release fat stores and not cause your body to go into a metabolic slow-down. Conversely -- if you go on a diet, without the band --and that part of the stomach is not stretched, your hypothalamus thinks you are in a famine -- it doesn't know that there is a lot of food around you.

The purpose of banding is weight loss. Patients who are successful do not "feel tight," or "feel restricted." Instead, successful patients report that they rarely have an issue with the band, they do not "feel restriction."   Successful patients come for adjustments when they notice that their appetite is returning between meals -- patients who are not successful rely upon the band to tell them when to stop eating.

The band, in successful patients, is empowering. While, on occasions, the band is "fickle" the proper way for the band to work is for it to allow you to eat less and not be moved by an appetite.

There is another group of Lap-band patients who do not like any sensation of restriction

--a group we call volume eaters. They want to eat a lot, when they want to eat, and they do not like the sensation of a "hard stop."  Nor does this group want to eat a small volume and walk away and allow their appetite to be suppressed. One patient even asked for pills for nausea, because she could not eat "a quart of chili." Yes, this person thought a quart was a normal serving size -- not a cup, a quart!   Sometimes these patients come in for an adjustment, then come back thinking that the band is too tight, because when they overeat they become acutely uncomfortable, or feel as if they are "obstructed."  Often these patients will come in for a fill, then an unfill, then another fill.

It does take a bit of work to change a person's perspective about the volume of food they eat. For some there is a feeling of deprivation, a period of mourning, but ultimately the band can become a tool to overcome this sensation, and allow the patient to eat. Remember, if you want to be a 125 pound person, you have to eat like one.  The band allows your body to re-set the thermostat to the amount of food that it takes to keep you satisfied between meals.

To be more specific - food does not stay in the pouch above the band for a long period of time.Typically it travels through this area fairly quickly, usually less than a couple of minutes. The effect of the band is NOT to have food stay above the stomach in that small pouch - the effect of the band is on your appetite after a small amount of food stimulates that. Does this mean you can eat more -- yes, you can. That is always in your control.