For example, in one study blood sugar levels of most obese patients with diabetes returned to normal after surgery. Nearly all patients whose blood sugar levels did not return to normal were older or had had diabetes for a long time. Abdominal hernias are the most common complications requiring follow-up surgery. Less common complications include breakdown of the staple line and stretched stomach outlets. More than one-third 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 is increased. Gallstones can be prevented with supplemental bile salts taken for the first six months after surgery. Nearly 30 percent of patients who have weight-loss surgery develop nutritional deficiencies such as anemia, osteoporosis, and metabolic bone disease. These deficiencies can be avoided if vitamin and mineral intakes are maintained. Women of childbearing age should avoid pregnancy until their weight becomes stable because rapid weight loss and nutritional deficiencies can harm a developing fetus.