Sleeve gastrectomy
Sleeve gastrectomy involves removing approximately 80% of the stomach, leaving a vertical tube in place, without altering the intestinal anatomy. It therefore acts primarily through restriction and hormonal modulation, without inducing nutritional malabsorption.
Bypass
Gastric bypass, on the other hand, combines stomach restriction with partial intestinal bypass. It involves creating a small gastric pouch connected directly to the jejunum, thus bypassing the remaining stomach, the duodenum, and part of the small intestine. This dual action—restrictive and malabsorptive—maximizes weight loss but also exposes patients to a higher risk of nutritional deficiencies, particularly iron, calcium, vitamin B12, and fat-soluble vitamins.
Sleeve, bypass : the differences
In terms of weight loss results, the two procedures are very similar in the medium term. Large randomized studies have not shown any significant difference in weight loss at five years. Excess weight loss is estimated at around 60 to 70% for both techniques, with a slight tendency in favor of bypass in the long term, particularly in certain metabolic profiles.
On the other hand, digestive tolerance differs significantly. Sleeve gastrectomy is associated with a higher frequency of gastroesophageal reflux after surgery. This phenomenon can be bothersome or even limiting for some patients, particularly in cases of pre-existing GERD. Conversely, bypass surgery has a favorable effect on reflux and can even be used as a surgical treatment for severe GERD. This is why bypass surgery is preferred in cases of significant reflux.
Finally, the question of choosing between the two procedures is always based on an individualized assessment. Several factors are taken into account: the presence of comorbidities (particularly GERD or diabetes), age, surgical history, patient preferences, possible follow-up, and nutritional profile. Thus, a young patient without reflux who is highly motivated may benefit from a sleeve gastrectomy, while a person with difficult-to-control diabetes or severe reflux will often be better suited to a gastric bypass.
In short, while sleeve gastrectomy is simpler, less invasive, and does not involve intestinal diversion, gastric bypass remains more effective in certain metabolic contexts, while requiring more follow-up. In both cases, the surgical risk is comparable for the two techniques. The choice is made in close consultation between the patient and the specialized team, after comprehensive and personalized information has been provided.