Obesity And Weight Loss Surgery
Margaret E. Woltjer, Ph.D. | March 2005

The treatment for obesity is simple: eat less, exercise more. Putting that into practice is more than a little challenging for many people. The challenge increases as the degree of obesity increases to the point that it overwhelms the individual. More and more, people are hearing about how the famous and not-so-famous have lost over 100 pounds and more through weight loss surgery. This option is not for everyone but rather for those who are diagnosed as morbidly obese. Morbid obesity is defined as a body-mass index (BMI) of 40 kg/m2 or greater(1). For those who fit this definition, weight loss surgery has become a viable option.

The type of weight loss surgery that is considered depends, in part, on how obese the individual is. There are four primary types of weight loss surgery: Gastric Bypass Surgery, Biliopancreatic Diversion, Lap Band (Gastric Banding), and Gastroplasty (Vertical Banded).

Differences among the Four Types of Surgery
Gastric Bypass: Also called Roux-en-Y Gastric Bypass, separates the stomach into two unequal compartments with less than 5% of the stomach remaining usable for food digestion thereby drastically limiting the amount of that can be eaten(2). This method seems to be the most popular of the four types in the US. Following surgery, food empties from the small remaining portion of stomach into the small intestine. Weight loss tends to occur more rapidly and continue over a longer period of time compared with other methods. The reason for this is the small degree of malabsorption that takes place because food will bypass most of the stomach and part of the upper small intestine. After a gastric bypass, the volume the smaller stomach will hold is reduced from about one quart to about two tablespoons. Successful weight loss occurs because the individual cannot eat too much food at a time and feels more satisfied after eating the smaller meals the remaining pouch can tolerate.

A less invasive form of gastric bypass involves a laparoscopic procedure wherein several small incisions are made instead of one large incision to perform the operation. Another version, called a distal gastric bypass, involves reconnecting the upper small intestine closer the colon, increasing malabsorption and the risk of nutritional complications. This procedure is available to patients who are more than 200 pounds overweight.

Biliopancreatic Diversion (BPD): This is a variation of the gastric bypass surgery in which about one half of the intestine is excluded (bypassed) before it is rejoined to the lower segment of the small intestine between two and four feet above the colon (large intestine), forming a common channel. Modifications have been made in BPD as well, depending upon the patient’s BMI and, at times, to decrease the problems associated with malabsorption.

Lap Band (Gastric Banding): The Lap Band procedure is the least invasive of the four procedures and carries the least risk. In this procedure the stomach is encircled with an inflatable, adjustable band, restricting the stomach’s capacity for holding food. The result is that the person feels fuller sooner. Since the restriction of the stomach is less than is involved in the Roux-en-Y or the BPD procedures, and because the intestine is not bypassed at all, weight loss is less dramatic and there is no malabsorption (2).

Gastroplasty (Vertical Banded Gastroplasty): In this procedure the upper stomach is stapled in a vertical direction with a pre-measured plastic band separating the upper and lower stomach, thus preventing the stomach from stretching at this point (1). This method has also been modified to be done as a laparoscopic procedure.

What to Expect After Surgery
The type of procedure will dictate what to expect since the various procedures involve different degrees of invasiveness. As with any surgery, adequate time and attention must be allowed for the recovery process. But because obesity surgery will alter the availability of nutrition by a conventional diet, particular attention must be given to eating patterns that will address nutritional needs.
  • Eating patterns must change. In general, the diet after surgery progresses from clear liquid to “full” liquid to a pureed diet to a soft diet and then to a modified, regular diet. The diet is designed to promote healing initially, and later to meet nutritional needs. To avoid the risk of complications, it is imperative that the diet be followed as ordered. In general, the initial diet includes foods high in protein, and low in fat, fiber, calories, and sugar. Supplements are given to replace the vitamins and minerals that will not be available in a typical gastric bypass diet (1,2).

  • Long-term eating goals must be addressed. Learning new eating habits and how to follow a diet correctly will help to maintain weight loss over time, but the entire process of what and how to eat is addressed as soon as food is introduced into the diet. Over the long-term, protein in the diet helps preserve muscle tissue so that weight can be lost as fat instead of muscle. Foods high in calories and fats are minimal because they make weight loss difficult and because they can promote “dumping”, the rapid elimination of food products which cannot be digested and absorbed (2). Meals must be eaten slowly and the food chewed into a liquidy mash. This is the time to pay attention to taste of food and how the amount eaten will feel. Over-eating will produce vomiting and pain (1,2).

  • Paying attention to fullness. Almost everyone who requires bypass surgery has had problems with overeating. While the causes of overeating are numerous, it will be necessary for the person who has had bypass surgery to address the problem to have a successful outcome. Eating more than the new stomach can hold can cause vomiting, expansion of the pouch, weight gain, and can even rupture the stomach. It will help to pay attention to the feeling of pressure or fullness just below the rib cage, or to any feelings of nausea, reflux or heartburn (1,2,3). The most common cause of vomiting is eating inappropriate foods, eating too fast, not chewing properly, eating too much at once, beginning on solids too soon, taking in liquids at the wrong times, or lying down too soon after eating.

  • Eating a balanced diet. As before the weight loss surgery, eating a balanced diet is still important. Since the quantity of food that is eaten is reduced, paying attention to what is eaten, when it is eaten, and how much is eaten is essential. The patient will be working closely with a dietician to outline an appropriate diet as new foods can be introduced (1,4).

  • Taking vitamins. Vitamin supplement will be a lifelong requirement after surgery and is started immediately. Your physician will prescribe these as your needs dictate (1,4).

  • Exercise. While strenuous activity must be avoided immediately after surgery, exercise will be gradually introduced as recovery from the procedure allows. In any case, daily exercise will eventually be expected.

Benefits and Risks of Weight Loss Surgery
While sufficient data is not yet available on many of the newer procedures, information regarding the pros and cons of each procedure should be discussed with the physician who can then make an appropriate recommendation in each specific case. The general health of a person will be considered, but in some cases the benefits of having the surgery may outweigh the risks even if the person’s health is poor (4).

Benefits of weight loss surgery include(1,2,4):
  • High blood pressure can be alleviated or entirely eliminated.

  • High Blood Cholesterol in the majority of patients can be reduced or eliminated in 2 to 3 months after surgery.

  • Diabetes Mellitus can usually be helped, along with the complications often associated with diabetes, depending on how severe the symptoms were before surgery.

  • Heart Disease is more prevalent among obese persons. While there is no data on the effects of weight loss surgery on someone who already has heart disease, it is expected that there would be a decrease in the progression of symptoms.

  • Borderline Diabetes can greatly benefit from weight loss surgery since it may be prevent the borderline symptoms from getting worse.

  • Asthma sufferers have found relief from attacks in that they eventually have fewer or none at all.

  • Sleep Apnea Syndrome sufferers also report a reduction or complete absence of symptoms within about a year.

  • Gastroesophageal Reflux Disease (GERD) is greatly reduced within a few days after surgery.

  • Stress Urinary Incontinence responds dramatically to weight loss surgery and is often completely controlled in time.

  • Low Back Pain, Degenerative Disk Disease, and Degenerative Joint Disease are all helped with weight loss, even after the loss of only 25 pounds.

Risks of weight loss surgery include(1,2,3,4):
  • This list necessarily includes any risk involved with nearly all operations (e.g., pneumonia, abscesses, wound infections). This list is included because among those who are morbidly obese, the risk is higher due to general physical condition, associated medical problems, and the presence of the deeper layer of fat under the skin.

  • Other relatively uncommon problems which sometimes appear with weight loss surgery are urinary tract infections, hemorrhage, bowel obstruction due to scars called adhesions, leakage of bowel contents due to an incomplete seal between fastenings, and obstruction of the stomach outlet if scars form in the area and constrict the opening too much.

  • Nutritional deficits can be avoided by taking proper vitamin and mineral supplements as prescribed by the physician, and by following dietary recommendations.

  • Protein deficiency occurs due to diminished food intake. This is often addressed by having the patient eat most of their protein intake in the first half of each meal.

  • Possible side effects may include nausea, food intolerance, “dumping syndrome”, and transient hair loss due to the drastic reduction of calories and subsequent weight loss (this corrects itself once the weight stabilizes).

  • Loss of muscle mass can occur when the body perceives that it’s starving. Under this threat the body will store fat and burn other forms of fuel first, including muscle. Loss of muscle is preventable. During active weight loss after surgery, loss of muscle mass can be avoided by exercising vigorously as soon as the doctor gives the okay.

General Issues
The success rate of weight loss surgery is fairly high with about 70-80% of patients achieving success of the long term (4). The decision of whether to have the surgery and what type it should be is made in consultation with your doctor. Not all surgeons perform all types of weight loss operations. If you are considering surgery, do your homework. Find out what your options are, who does the particular type of surgery recommended for you, how much experience the surgeon has in performing that type of operation, what type of preparation and follow-up you will have, and what the particular risks and benefits are in your case. Because weight loss surgery involves lifestyle change for the rest of your life if it is to be successful, you will need to take a great deal of responsibility for understanding how your body works and what you will need to modify for it to stay healthy.

Most gastric bypass patients experience fairly rapid weight loss in the first 3 to 6 months after surgery. After that it slows down but will continue for up to about 18 months after surgery. How long you can expect to experience ongoing weight loss depends upon the procedure used since in some cases the weight comes off slower, but over a longer period of time. To maintain any weight loss, it is critical to adhere to a prescribed diet and maintain an exercise program.

  1. American Society for Bariatric Surgery. Rationale for the Surgical Treatment of Obesity. Updated April6, 1998.
  2. Gastric Surgery for Severe Obesity. National Institute of Diabetes and Digestive and Kidney Diseases. NIH Publication NO.96-4006, April1996.
  3. FDA Talk Paper. FDA Approves Implanted Stomach Band to Treat Severe Obesity. June 2001.
  4. National Institutes of Health Consensus Development Conference Statement Online. Gastrointestinal Surgery for Severe Obesity. March 25-27, 1991; 9(1):1-20.
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