How common is it for someone to need a gastric bypass?

Very common. Less then 30% of the american population actually has a normal bmi. Obesity is a major epidemic in this country and is rapidly expanding, especially in the adolescent and preadolescent age groups.Surgery is performed in 1% or less of those individuals who are consider candidates for these procedures. Surgery for obesity, especially over the last ten years has become increasingly more popular.
Bariatric Surgery. Less than 17% of morbidly obese individuals satisfy the criteria for bariatric surgery. Though the surgeons and "centers" performing these procedures would like it to be thought of otherwise this is a last ditch effort for those persons who have failed at every other possible weight loss effort---- this surgery is no walk in the park, has many life long consequences.