It may be the special diet adopted by gastric bypass patients, not the surgery itself, that results in many of the biggest benefits associated with the weight loss procedure, according to a new study. The findings come from Lund University, where one of the study’s lead authors Nils Wierup explained, “What we previously thought was an effect of the operation is actually due to the diet.”
Gastric bypass surgery — a procedure that makes the stomach smaller and re-routes the small intestine — isn’t just associated with weight loss, but also important metabolic changes that include an improvement in the body’s ability to handle blood glucose and potentially the rapid reversal of type-2 diabetes.
These have largely been thought to be the result of both the strict diet that someone adopts before the procedure, as well as the procedure itself. However, this new study looks into each aspect separately and has found that the majority of these benefits can be linked to the special pre-surgery diet itself, not the gastric bypass procedure.
Peter Spégel, one of the study leads, explains, “More than 90-percent of everything that occurred, happened as a result of the diet. Very little changed after the surgery.” This is contrary to the previous belief that hormone changes caused by the surgery played a big role in these beneficial outcomes.
However, there is a ‘catch’ in the sense that many people aren’t able to stick with a low-calorie diet for a long period of time, particularly if they have trouble controlling their impulses around food. The gastric bypass surgery makes things easier by reducing the size of the stomach and how much food it takes for the person to feel satisfied.
Beyond that, the surgery itself does impart a certain degree of benefits not related to the diet, namely an increase in the hormones GIP and GLP-1. Additional research will explore the function of these two hormones to determine what role they may play in the patient’s health changes.
As for the diet itself, gastric bypass patients usually are first put on a six-week diet that involves consuming limited foods and fewer than 1,000 calories daily. This is intended to cause weight loss and shrink the liver, making it easier to perform the surgery.