The term stomach-reduction-surgery refers to a type of bariatric surgery, such as gastric bypass, sleeve gastrectomy, or gastric band, performed in obesity cases to reduce the stomach pouch and limit the amount of food intake.
For patients meeting BMI criteria, weight loss surgery may carry fewer risks than severe obesity.
A stomach reduction surgery, also called a bariatric procedure, is performed in cases of obesity when diet and exercise alone are not effective. But when exactly does this type of weight‑loss surgery apply?
In Germany, approximately 62 percent of men and 43 percent of women are currently overweight, corresponding to a BMI above 30. Around 25 percent of all adults are classified as obese starting from a BMI over 30. The number of overweight individuals has increased significantly in recent years, primarily due to lack of physical activity and an unhealthy, high‑calorie diet.
The Body Mass Index (BMI) is calculated from height and weight (body weight [kg] / height squared [m²]) and is widely used in medicine for classifying body weight. A BMI between 20 and 25 is considered a medically healthy ideal body weight. From a BMI of 30 onwards, the condition is classified as obesity. Obesity is divided into three grades:
Long‑term obesity often requires bariatric surgery procedures such as gastric sleeve surgery, roux‑en‑y gastric bypass, mini gastric bypass, or laparoscopic adjustable gastric banding. These surgeries reduce the size of the stomach or bypass most of the stomach to help patients lose a significant percent of their excess body weight.
Without intervention, excess body weight can lead to comorbidities such as high blood pressure, lipid metabolism disorders (including elevated cholesterol), cardiovascular disease, or diabetes mellitus with late complications affecting kidneys, nerves, blood vessels, and eyes. For many patients, metabolic and bariatric surgery is the most effective weight‑loss procedure, offering rapid weight loss and long‑term health benefits.
Obesity is defined as severe overweight that is harmful to health. @ BillionPhotos.com /AdobeStock
Many people with severe excess weight are unable to achieve effective weight loss despite diet and exercise. Because the long‑term consequences of obesity often lead to serious health problems, bariatric surgery procedures can help. This type of surgery for obesity reduces the portion of the stomach, creating a smaller stomach that lowers calorie and nutrient intake. As a result, patients feel full more quickly and can experience rapid weight loss within months after surgery. The term “bariatric” is derived from the ancient Greek word baros, meaning “weight,” highlighting its role in helping patients reduce excess body weight and improve long‑term health.
Bariatric surgery is performed exclusively in patients with severe obesity, starting at a body mass index (BMI) of 35 or higher. This type of bariatric surgery is considered only after at least 24 months of conservative treatment, such as diet and exercise combined with nutritional counseling. Only when these requirements are fulfilled can bariatric surgery be considered.
Before surgery, treatable causes of obesity such as hypothyroidism or other hormonal disorders must be ruled out. A bariatric surgeon will evaluate whether options like roux-en-y gastric bypass, laparoscopic gastric bypass, or gastric sleeve surgery are suitable.
However, disadvantages of surgery for weight loss include possible complications during or after the operation, as well as long‑term risks such as nutrient deficiencies or digestive problems. In some cases, surgery may not be possible due to underlying health conditions, even though metabolic and bariatric surgery is often the most effective weight‑loss procedure for patients with severe excess weight.
Stomach surgery generally belongs to the field of visceral surgery and specifically gastroenterology. Within this specialty, surgeons can focus on this type of weight-loss surgery for patients with severe obesity and become certified bariatric surgeons. These operations are recognized as effective weight‑loss procedures that help patients lose weight and achieve long‑term weight loss.
To provide the best outcomes, many hospitals have specialized bariatric centers. In these clinics, experts in metabolic and bariatric surgery work together interdisciplinarily, combining knowledge, these centers bring extensive expertise under one roof to help patients reduce excess weight and improve overall health.
The most common types of bariatric surgery are:
In gastric bypass surgery, the stomach is reduced, and the small intestine is shortened. @ sakurra /AdobeStock
In a sleeve gastrectomy, a large portion of the stomach is removed, leaving a tube‑shaped smaller stomach pouch. This type of bariatric surgery reduces stomach volume and is considered restrictive, as it limits the amount of food intake to small portions.
The gastric bypass is a procedure in which, besides reducing stomach size, part of the small intestine is bypassed. This shortens the absorption length, leading to significant weight loss and improved blood sugar levels. Variants such as the roux-en-y gastric bypass or mini gastric bypass are commonly performed bariatric procedures.
In gastric banding, a band is placed around the top of the stomach and connected via a tube to a port under the skin. This allows adjustment by adding or removing fluid, regulating the passage of food from the stomach pouch to the rest of the stomach.
All four techniques can be performed as laparoscopic surgery (keyhole surgery). This minimally invasive method requires only small incisions instead of open surgery, resulting in less pain, faster recovery, and earlier discharge from the hospital.
A gastric balloon can also be placed as a minimally invasive procedure to support long‑term weight loss in patients with excess weight who have tried to lose weight through diet and exercise.
Every type of bariatric surgery carries some risk, albeit low. Perioperative risks (those occurring around the time of surgery) and possible complications include wound healing problems or cardiovascular issues such as thrombosis.
Possible late complications include adhesions or incisional hernias. However, the risk of such complications has been significantly reduced through laparoscopic gastric bypass procedures, gastric sleeve surgery, and other minimally invasive bariatric surgery procedures.
Overall, for patients with excess body weight who meet the criteria for surgery for obesity, the risks of the procedure are considered lower compared to the long‑term consequences of morbid obesity. In fact, metabolic and bariatric surgery often leads to effective weight loss and helps patients achieve or approach their ideal body weight.
Nevertheless, the advantages and disadvantages of each weight loss procedure should always be thoroughly discussed with the surgeon. Professional guidance from experts in bariatric and metabolic surgery, ensures patients understand how gastric bypass works, what portion of the stomach is reduced, and how bariatric procedures compare to diet and exercise alone.
Postoperative medical follow‑up is essential after any stomach reduction procedure. After gastric bypass surgery, and often after sleeve gastrectomy, the body requires lifelong supplementation of vitamin B12. This supplementation is usually administered as an injection every three months to support patients who have undergone bariatric surgery and now live with a new stomach that absorbs nutrients differently.
The position of a gastric band should be checked regularly via endoscopy, i.e., through a gastroscopy. Such monitoring ensures that the device remains correctly placed around the part of the stomach involved in restriction.
Following bariatric surgery, patients must permanently change their eating and dietary habits to achieve long‑term weight loss. In general, a consistent dietary adjustment under medical supervision is essential. This not only means consuming less food but also making conscious food choices to ensure a balanced intake of all essential nutrients.
Long‑term success after surgery for obesity depends on adapting to the smaller capacity of the new stomach and maintaining healthy lifestyle changes that support sustainable weight‑loss results.
The effectiveness of bariatric procedures varies by method, yet numerous clinical studies clearly document their success. With sustained weight loss, comorbidities such as high blood pressure, diabetes mellitus, and lipid metabolism disorders (including high cholesterol) generally show marked improvement.
The cost of bariatric surgery procedures depends on the chosen type of surgery and typically ranges between €8,000 and €15,000. Under certain conditions, these expenses may be covered by health insurance. Patients with a BMI over 40, or those with a BMI above 35 combined with severe comorbidities, can apply for coverage of their surgery for obesity.
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