How a Stomach is Rearranged in RNY Surgery For Weight Loss
June 10, 2020The first RNY surgery (gastric bypass surgery) was performed in 1954 and has since evolved with changes in technique, as well as the introduction of newer generations of surgical technology and advances in research, to its current iteration.
Introduced in the 1990s, the RNY surgery (laparoscopic Roux-en-Y gastric bypass, is now one of the most common types of bariatric surgery in the United States. he RNY surgery uses five small incisions (varying in length between an eraser head to a pinky tip) and carbon dioxide gas to inflate the abdomen like a balloon.
This minimally invasive approach allows for a faster healing time, improved pain control, decreased rates for infection and a dramatically reduced blood loss (often times less than a bottle cap in volume).
In short, the Roux-En-Y gastric bypass has advanced, even in the last five years, into the safe procedure that it is today.
The gastric bypass involves operating on two organs: the stomach and the small intestine. A small gastric pouch (about the size of a large egg) is created and separated from the rest of the stomach, which remains in the body.
For reference, a normal stomach expands to approximately one liter in volume. Next, the length of the small intestine is disconnected and rerouted, the bottom loop of the intestine is joined to the small stomach pouch and the top end of the intestine is reconnected to a more distant portion of the small intestine.
Absorption of calories and nutrients occurs when consumed food mixes with secretions from the stomach, liver, and pancreas; this process occurs much later in the digestive tract of people with gastric bypass anatomy.
Food goes down the new Roux limb (part of the intestine that connects to the small stomach pouch) and digestive enzymes travel its normal pathway along the biliopancreatic limb; the two streams only mix at the common channel. Each case is different but the surgery can take about one to two hours to perform.
Weight Loss After RNY
The weight loss after gastric bypass surgery occurs in a number of ways and involves restrictive, malabsorptive and hormonal mechanisms of action.
First, since the part of the stomach that holds food is now smaller, a lot less volume is needed to satisfy your appetite. These significantly smaller meals translate into less calories consumed.
In addition to feeling full sooner after eating, only a percentage of calories are absorbed from the consumed food since most of the stomach and the first section of the small intestine are bypassed. The amount of intestine bypassed is not enough to create malabsorption of protein or other macronutrients. Nonetheless, supplemental multivitamins with iron, calcium and vitamin B-12 are required.
Dumping is another mechanism for weight loss after gastric bypass. Dumping syndrome may result in lightheadedness, palpitations, nausea, diarrhea and other symptoms within 10 to 30 minutes after eating a high concentration of sugar. This rather unpleasant, but short-lived, reaction is a type of negative reinforcement and a reminder to moderate those high-calorie food items that have a great impact on weight.
Most people also experience a reduction in appetite and cravings for sweets and other less than ideal food items due to changes in chemical signaling between the gastrointestinal tract and hunger centers in the brain.
The rerouting of the food stream produces changes in gut hormones to promote feelings of fullness and satisfaction, as well as suppressing hunger. The way of life after gastric bypass surgery, therefore, is not necessarily a diet of deprivation and, in most cases, is a very comfortable lifestyle.
Long-Term Success of RNY Surgery
That being said, just like obesity is related to multiple contributing factors, reduced caloric intake does not provide a complete explanation of the long-term success of the gastric bypass.
Body weight is tightly coordinated within a narrow range by a complex regulatory network of biological signals that control digestion, appetite, metabolic rate and energy balance. These internal processes determine your body weight set point. Dietary weight loss below this set point causes this system to increase hunger and decrease metabolic rate, which ultimately results in weight regain back up to, and often times higher than, this set-point.
To achieve significant long-term weight loss, the body weight regulation system must be reset to prevent the storage of excess fat. The procedure, in fact, leads to conditions that increase the number of calories burned- most notably at mealtime.
After gastric bypass, the digestive system then uses even more energy to break down food and absorb nutrients. So eating actually helps to lose weight, unlike dietary weight loss. Losing weight with gastric bypass, therefore, has a greater chance of long term success because an appropriate energy balance is created.
In short, gastric bypass surgery reprograms the body weight defense mechanism.
The decision to have bariatric surgery is oftentimes not an easy one to make. It takes blood, sweat, and tears (sometimes literally) to make that initial consultation.
However, with the willingness and commitment to make long-term behavioral changes, continued follow-up to monitor nutrition, lifestyle and habits, the gastric bypass can be a very powerful tool to lead a healthier and happier life.
 | ABOUT THE AUTHOR Dr. Michael Donaire specializes in laparoscopic Roux-en-Y gastric bypass, laparoscopic sleeve gastrectomy, and laparoscopic gastric banding, as well as other advanced minimally invasive and general surgery procedures at Advanced Surgical and Bariatrics in Somerset, NJ. With a Master of Public Health background, his philosophy on comprehensive care supports patients in their journey to a healthier life. He completed the Bariatric and Advanced Gastrointestinal Minimally Invasive Surgery Fellowship at the State University of New York Health Science Center in Brooklyn, NY. |
