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Weight Loss Surgery Health Center

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An Overview of Weight Loss Surgery

Benefits and Risks of Weight Loss Surgery

Weight loss surgery is a serious undertaking. Before making a decision, talk to your doctor about the following benefits and risks.


  • Weight loss: Immediately following surgery, most patients lose weight rapidly and continue to do so until 18 to 24 months after the procedure. Although most patients then start to regain some of their lost weight, few regain it all.
  • Obesity-related conditions improve: For example, recent research has shown that in obese patients with diabetes, bariatric surgery resulted in better blood sugar control than medication. This held true no matter what the person weighed before surgery, or how much weight they were able to lose.  

Risks and Side Effects

  • Vomiting: This is a common risk of restrictive surgery caused by the small stomach being overly stretched by food particles that have not been chewed well.
  • "Dumping syndrome”: Caused by malabsorptive surgery, this is when stomach contents move too rapidly through the small intestine. Symptoms include nausea, weakness, sweating, faintness and, occasionally, diarrhea after eating, as well as the inability to eat sweets without becoming extremely weak.
  • Nutritional deficiencies: Patients who have weight loss surgery may develop nutritional deficiencies such as anemia, osteoporosis, and metabolic bone disease. These deficiencies can be avoided if vitamin and mineral intakes are maintained.
  • Complications: Some patients who have weight loss operations require follow-up operations to correct complications. Complications can include abdominal hernias, infections, breakdown of the staple line (used to make the stomach smaller), and stretched stomach outlets (when the stomach returns to its normal size).
  • Gallstones: More than 1/3 of obese patients who have gastric surgery develop gallstones. Gallstones are clumps of cholesterol and other matter that form in the gallbladder. During rapid or substantial weight loss a person's risk of developing gallstones increases. Sometimes this can be prevented by taking supplemental bile salts for the first 6 months after surgery.
  • Need to temporarily avoid pregnancy: Women of childbearing age should avoid pregnancy until their weight becomes stable because rapid weight loss and nutritional deficiencies can harm a developing fetus.
  • Side effects: These include nausea, vomiting, bloating, diarrhea, excessive sweating, increased gas, and dizziness.
  • Lifestyle changes: Patients with extensive bypasses of the normal digestive process require not only close monitoring, but also life-long diet and exercise modifications and vitamin and mineral supplementation.

Am I a Candidate Weight Loss Surgery?

If you have a body mass index (BMI) of 40 or more -- which is about 100 pounds overweight for men and about 80 pounds for women -- you are considered severely obese and therefore a candidate for weight loss surgery.

Obesity surgery may also be an option for people with a BMI of 35 to 40 who suffer from obesity-related problems (for example, severe sleep apnea, obesity-related heart disease, or diabetes). For these people, the risk of death from not having the surgery may be greater than the risks from the possible complications from undergoing the procedures.

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