gastric bypass
What is Gastric Bypass?
Gastric bypass surgery is a well-established type of bariatric surgery designed to help individuals with severe obesity achieve significant and sustained weight loss. It works by altering the normal anatomy and physiology of the digestive system, specifically the stomach and small intestine, to reduce food intake and nutrient absorption.
How Does Gastric Bypass Work?
Gastric bypass involves two primary mechanisms:
1. Creation of a Small Stomach Pouch (Restriction)
During the surgery, the surgeon divides the stomach to create a much smaller pouch at the top — typically about the size of a walnut or an egg (around 15-30 milliliters in volume). This small pouch acts as the “new stomach” and limits the amount of food you can eat at one time. Because the pouch is much smaller than a normal stomach, it fills quickly, which helps you feel full faster and reduces overall food intake.
2. Bypassing a Portion of the Small Intestine (Malabsorption)
The surgeon then reroutes part of the small intestine, connecting it directly to the small stomach pouch. This means that food bypasses a significant portion of the stomach and the upper small intestine (duodenum and part of the jejunum). Because the food skips this section, fewer calories and nutrients are absorbed during digestion.
Hormonal and Metabolic Effects
Beyond just physical changes, gastric bypass surgery also impacts gut hormones that regulate hunger and satiety. For example, it can:
Reduce the hormone ghrelin, which stimulates appetite
Increase hormones that promote fullness and improve blood sugar control, like GLP-1
These hormonal changes contribute to reduced hunger, better glucose metabolism, and often improvement or remission of type 2 diabetes.
What Are the Results?
Because of the combined effects of:
Smaller stomach capacity (you eat less)
Reduced calorie absorption (you absorb less energy from food)
Hormonal changes (less hunger, better metabolism)
Most patients experience significant and sustained weight loss, often losing 60-80% of their excess body weight within 12-18 months.
Who Is Gastric Bypass For?
Gastric bypass is typically recommended for people who:
Have a Body Mass Index (BMI) of 40 or higher (severe obesity)
Have a BMI of 35 or higher with obesity-related health problems like type 2 diabetes, high blood pressure, sleep apnea, or heart disease
Have tried other weight loss methods such as diet, exercise, or medication but struggled to maintain results
Are committed to long-term lifestyle changes and follow-up care