What health problems are needed in order to qualify for gastric bypass surgery?

What types of health problems are needed to qualify to have gastric bypass surgery? Do you only qualify if you have severe health problems caused by this or could you qualify if you have smaller health problems like knee arthritis & breathing problems? Most of my family is obese and have heart disease, sleep apnea. Would they take that into consideration? My sister had gastric bypass surgery with a starting weight at 208 and is down to 128. I don't think she had any medical problems due to her obesity.

Usually you have to have a BMI (Body Mass Index) of 40 or more to qualify for gastric bypass. If you have a BMI of over 35, sometimes you can qualify if you have significant co-morbidities such as diabetes or sleep apnea. First and foremost, "they" look at how morbid obesity is affecting you, however, your family history may be taken into account, if close relatives are morbidly obese and have health problems relating to obesity.