To understand how surgical procedures aid the grossly overweight person to reduce their body fat, it helps to first understand the digestive process that is responsible for handling the food we take in.
Once food is chewed and swallowed, it's on its way through the digestive tract, where enzymes and digestive juices will break it down and allow our systems to absorb the nutrients and calories. In the stomach, which can hold up to three pints of material, the breakdown continues with the help of strong acids. From there it moves into the duodenum, and the digestive process speeds up through the addition of bile and pancreatic juices. It's here, that our body absorbs the majority of iron and calcium in the foods we eat. The final part of the digestive process takes place in the 20 feet of small intestine, the jejunum and the ileum, where calorie and nutrient absorption is completed, and any unused particles of food are then shunted into the large intestine for elimination.
Weight loss procedures involve bypassing, or in some way circumventing the full digestive process. They range from simple reduction of the amount you can eat, to major bypasses in the digestive tract. To qualify for many of these surgeries, a person must be termed "morbidly obese", that is, weighing at least 100 lbs. over the appropriate weight for their height and general body structure.
In the mid 1960s, Dr. Edward E. Mason discovered that women who had undergone partial stomach removal as the result of peptic ulcers, failed to gain weight afterwards. From this observation, grew the trial use of stapling across the top of the stomach, to reduce its actual capacity to about three tablespoons. The stomach filled quickly, and eventually emptied into the lower portion, completing the digestive process in the normal way.
Over the years, the surgery evolved into what is now known as the Roux-en-y Gastric Bypass. Instead of partitioning the stomach, it is divided and separated from the rest, with staples. The small intestine is then cut at approximately 18" below the stomach, and attached to the "new", small stomach. Smaller meals are then eaten, and the digested food moves directly into the lower part of the bowel. As weight loss surgeries are viewed overall, this is considered one of the safest, offering long-term management of obesity.
A procedure that produces basically the same results as the stomach stapling/bypass, and is also classed as a "restrictive" surgery. The first operations, involved a non-flexing band placed around the upper part of the stomach, below the esophagus, creating an hourglass shaped stomach, the upper portion being reduced to the same 3-6 ounce capacity. As technologies advanced, the band became more flexible, incorporating an inflatable balloon, which when triggered by a reservoir placed in the abdomen, was capable of inflating to cut down the size of the stoma, or deflating to enlarge it. Laparoscopic surgery means smaller scars, and less invasion of the digestive tract.
A combination of the gastric bypass, and Roux-en-y re-structuring, that bypasses a significant section of the small intestine, thereby creating the probability of malabsorption. The stomach is reduced in size, and an extended Roux-en-y anastomosis is attached to the smaller stomach, and lower down on the small intestine than is normal. This permits the patient to eat larger amounts, but still achieve weight loss through malabsorption. Professor Nicola Scopinaro, University of Genoa, Italy, developed the technique, and last year published the first long-term results. They showed an average 72% loss of excess body weight, maintained over 18 years, the best long-term results of any bariatric surgical procedure, to date. BPD patients require lifelong follow-ups to monitor calcium and vitamin intake. The advantages of being able to eat more and still lose weight, are countered by loose or foul smelling stools, flatus, stomal ulcers, and possible protein malnutrition.
One of the first weight loss procedures for the grossly obese, was developed in the 1960s, a strictly malabsorptive method of reducing weight, and preventing gain. The jejuno-ileal bypass reduced the lower digestive tract to a mere 18" of small intestine, from the natural 20 feet, a critical difference when it came to absorption of calories and nutrients. In the end-to-end method, the upper intestine was severed below the stomach, and re-attached to the small intestine much lower down, which had also been severed, thereby "cutting out", the majority of the intestine. Malabsorption of carbohydrate, protein, lipids, minerals and vitamins, led to a variation, the end-to-side bypass, which took the end of the upper portion, and attached it to the side of the lower portion, without severing at that point. Reflux of bowel contents into the non-functioning upper portion of small bowel, resulted in more absorption of essential nutrients, but also less weight loss, and increased weight gain, post-surgery. As a result of the bypass, fatty acids are dumped in the colon, producing an irritation that causes water and electrolytes to flood the bowel, ending in chronic diarrhea. The bile salt pool necessary to keeping cholesterol in solution is reduced by malabsorption and loss through stool. As a consequence, cholesterol concentration in the gall bladder rises, increasing the risk of stones. Multiple vitamin losses are a major concern, and may result in bone thinning, pain and fractures. Approximately one third of patients experience an adjustment in the size and thickness of the remaining active small intestine, which increases the absorption of nutrients, and balances out the weight loss. However, over the long term, all patients undergoing this bypass are susceptible to hepatic cirrhosis. In the early 1980s, one study showed that approximately 20% of those who had undergone JIB, required conversion to another bypass alternative. The procedure has since been largely abandoned, as having too many risk factors.
While surgical methods of reducing weight are valuable to the morbidly obese, they are not without risks. Patients may require more bed rest post-surgery, resulting in an increased chance of blood clots. Pain may also cause reduced depth of breathing, and complications such as pneumonia.
Before undergoing any fat/weight reduction surgery, a severely overweight person needs to thoroughly understand the benefits and risks, and must make a commitment to their future health. Having a smaller stomach is not going to stop the chronic sugar-snacker, from "grazing" on high calorie sweets. Nor does a steady supply of pop, concentrated sweet juices and milk shakes, reduce the calorie intake. With some bypass surgeries, certain foods can aggravate side-effects that need not be that severe, if common sense diets are adhered to. Surgery can be a "shortcut" to weight loss, but it can also reduce your enjoyment of life, if you are unable to adhere to the regimens that go with it.