HOW YOUR STOMACH COMMUNICATES WITH YOUR BRAIN

     Our media are now full of articles about the epidemic of overweight in our society.  Recent estimates indicate that the overweight person loses as much as 15 years of their life because of the excessive weight some people carry. The diet prescriptions continue proliferate with the latest craze being the “Atkins Diet”.  It used to be that people talked about low fat diets, now they talk about low carbohydrate diets.  As 98% of the people who ever tried it know, diets don’t work and yet our society persists in their basic approach that the overweight person is simply undisciplined and eats too much.  When I was in medical school, there were two professors who were very disciplined individuals.  One was 6 feet 3 inches tall and weighed 175 lbs.  The other was about 6 feet tall weight over 250 lbs.  They compared their diets and found that in fact they both took in about the same number of calories yet on stayed thin and the other stayed heavy.

     The answer to how this difference occurs is turning out to be much more hormonally decided than we thought.  There have now been four separate hormones that have been identified that impact a person’s eating habits.  These hormones can have an effect within the hour of the time that they are secreted.  The first of these is insulin.  The overweight diabetic is already secreting 3-4 times the amount of insulin a normal person secretes.  The puzzle of this, is while the blood sugar lowering part of insulin seems to be less effective, the appetite part seems to stay and the overweight diabetic has a built in hormonal stimulant to eat.  The answer to this dilemma is to become more sensitive to the amount of insulin that a person has through the use of exercise or various medications.  Thereby the person secretes less insulin and has less appetite stimulation.

     The second hormone found is one called Lepton.  This is a hormone that is secreted by fat cells and it decreases a person’s appetite. The heavier the person becomes with fat cells, the more lepton is secreted and in a normal situation, a person eats less.  Unfortunately, this hormone is only really effective in a thin person.  It seems as though the person who is overweight, is again less sensitive to the lepton that they have almost certainly related to genetic consideration.  Unfortunately, there is no conceptual way to improve lepton sensitivity in today’s world.  Perhaps in the future, pharmaceutical companies will develop a lepton look alike molecule that will be more effective.

     The third hormone discovered in the last five years is called ghrelin    I have written a previous column about this very interesting hormone that the stomach secretes when it remains empty.  Ghrelin stimulates appetite leaving the person to eat more.  The one discovery that is help for this hormone is the gastric bypass surgery.  It seems that individuals who have had their stomachs bypassed surgically, cease to secrete this hormone and their appetite decreases substantially.  This is felt to be a strong factor in the weight loss associated with gastric bypass surgery.

     More recently, a hormone secreted by the intestine called PYY has been further studied.  Different than other hormones studied thus far, this hormone seems to work in both lean and heavy individuals.  It seems to be made less by heavy individuals and when given to a person who is heavier, they eat less.  While this hormone was discovered almost 20 years ago, it characterization has taken an extended period of time.  As you might imagine, pharmaceutical companies are working feverish to bring this product to the market.

 Thus, what a person eats seems to be under voluntary control, in fact there are at least 4 separate hormones and certainly more that impact a person’s appetite and influence how much they eat.  The variations in the weight of our population is at least partially related to how sensitive the person is to the hormones they have and how much of those hormones they make.  There is no question that some individuals are born genically predisposed to be heavier and some individuals are genetically determined to weigh less.

     Just as medical science unseated infection as the leading cause of death in our world and we are currently unseating heart disease the leading cause of death, developments will come whereby these hormonal mediated effects on your weight can be controlled.  Indeed the hormones can be dealt with through will power as dieters often learn.  But remaining on an abnormal pattern of eating for a long time, is not something that normal people do.  Unfortunately, the hormones always seem to be there.

     As a closing note, it is always said that in order to lose weight, a person has to diet and exercise.  I am a strong advocate of exercise but it is a very weak answer to weight loss.  Specifically, you burn approximately 100 calories for every mile that you walk.  In order to lose one pound of fact worth 4,000 calories, you have to walk 40 miles.  I don’t know anybody that does that.  But if you look at the normal calorie intake per day of around 2500 calories, split between 3 meals, it turns out that a person takes in between 5 and 800 calories per meal, skipping one meal is worth an awful lot of walking.

     Next week, I will discuss the pharmacologic solution available for the overweight problem.  On Saturday morning, December 6, 2003, there will be a discussion at the Medicine Rock Café in Gettysburg on overweight problems and methods people can use to help deal with that problem.  Preparing a month and a half for that New Years Resolution, may give you a better start.