Most obesity centers have very specific eligibility criteria for their surgical patients. Usually, to be eligible for gastric bypass surgery you would need to have a BMI (Body Mass Index) of 40 or more, or a BMI of 35 to 39.9 with obesity related illnesses. What, exactly, is an obesity-related illness?

When most people think of a condition related to obesity they think of diabetes and heart disease. Both of these conditions have shown improvement for many patients after gastric bypass and gastric banding surgeries. However, there are other illnesses that may make you eligible for weight loss surgery. Your surgeon will look at your overall health and all current conditions before determining if you are a good candidate for these procedures.

Some of the conditions that may be caused or related to obesity are listed below. You'll note that many of these conditions affect the heart.

Elevated cholesterol and triglycerides, which may be associated with a higher risk for heart disease and stroke.

Gallstones. Although gallstones are considered an obesity-related illness, this is also one of the possible complications of gastric bypass surgery because of the fast weight loss experienced by post-surgical patients.

Pancreatitis, or inflammation of the pancreas, a large gland that secretes digestive enzymes in to the small intestine.

Abdominal hernias. Sudden weight loss can also cause hernias, which develop at weak spots in the abdominal wall.

Fatty liver disease, which is often associated with alcoholism, can also be caused by obesity. It is thought that the liver damage may be due to insulin resistance, which is also common in obese patients.

Diabetes and prediabetes, which may also be related to insulin resistance in obese patients.

Polycystic ovary syndrome, which can affect the menstrual cycle, hormone balance, insulin production, heart, blood vessels, fertility, and appearance (acne). Obesity is considered one of the symptoms of this syndrome, which affects 5 to 10% of women who are of childbearing age.

High blood pressure, which affects 70% of obese patients.

Coronary heart disease, which can lead to a heart attack. Obesity is considered a major risk factor for heart disease.

Pulmonary hypertension, or high blood pressure in the arteries that supply the lungs.

Stroke, the third leading cause of death and disability in the United States. A recent study found that a man with a BMI of 30 or higher is twice as likely to have a stroke as a man with a BMI of less than 23.

Blood clots in the legs and lungs. This is another condition that is both an obesity-related illness and a common risk associated with surgery.

Sleep apnea, which affects obese men more than women. Over 95% of patients diagnoses with sleep apnea are overweight.

Knee osteoarthritis. Obese patients have 4 to 5 times greater risk for this condition.

Gout, an extremely painful condition caused by the deposit of uric acid crystals in joints and tissue.

Lower back pain, caused by carrying excess weight.

Infertility, in both men and women.

This is only a partial list of obesity-related conditions that may be considered by your surgeon when determining if you're eligible for bariatric surgery. Many of these conditions may go away or improve dramatically after a gastric bypass procedure and the subsequent weight loss.