How Surgery Reduces Weight

Surgeons first began to recognize the potential for surgical weight loss while performing operations that required the removal of large segments of a patient's stomach and intestine. After the surgery, doctors noticed that in many cases patients were unable to maintain their pre-surgical weight. With further study, surgeons were able to recommend similar modifications that could be safely used to produce weight loss in morbidly obese patients. Over the last decade these procedures have been continually refined in order to improve results and minimize risks. Today's bariatric surgeons have access to a substantial body of clinical data to help them determine which surgeries should be used and why.

Two basic categories for weight loss surgery.

  1. Restrictive procedures that decrease food intake

  2. Alabsorptive procedures that alter digestion, thus causing the food to be poorly digested and incompletely absorbed. 

Restrictive procedures

The theory is simple. When you feel full, you are more likely to have reduced feelings of hunger and will no longer feel deprived. The result is that you are likely to eat less. Restrictive weight loss surgery works by reducing the amount of food consumed at one time. It does not interfere with the normal absorption (digestion) of food.  A well informed, knowledgeable, and compliant patient, the reduced stomach capacity, along with behavioral changes, can result in consistently lower caloric intake and consistent weight loss.

During recovery, patients must adhere to the strict specific dietary guidelines and restrictions their bariatric surgeon prescribes. When the time comes to resume eating "regular" food, the patient must learn to adapt to a new way of eating.  Patients who see the best results from a restrictive procedure are those who learn to eat slowly, eat less, and avoid drinking high calorie fluids and carbonated beverages. If the patient fails to follow these guidelines, they can stretch the stomach pouch and/or the stoma outlet and defeat the purpose of the surgery. The effectiveness of a restrictive procedure is reduced by over eating, constant snacking,  drinking high-calorie drinks, or consuming high-fat high calorie foods. Failure to achieve the expected level of weight loss is usually the result of a patient failing to comply with the recommended dietary and behavior modifications, such as increased exercise and regular support group attendance.

Malabsorptive procedures that alter digestion

A malabsorptive procedure alters digestion. Malabsorptive procedures were developed to work in conjunction with restrictive procedures.  Some of these techniques involve a bypass of the small intestine, thus limiting the absorption of calories. The risk of complications and side effects generally increases with the lengthening of the small intestine bypass.

You and your bariatric surgeon must determine the risks and benefits over your lifetime with the type of weight loss surgery you choose.

Basically, weight loss operations fall into three categories:

  • Restrictive procedures make the stomach smaller to limit the amount of food intake.
  • Malabsorptive techniques reduce the amount of intestine that comes in contact with food so that the body absorbs fewer calories.
  • Combination operations take advantage of both restriction and malabsorption