What determines if gastric bypass was successful?

Ask Bariatric surgeo: I guess the success is the lost of weight and the improvement in the numbers of the glucose (a1c) and improvement in blood pressure and the lack of complications vomiting , dehydration , formation of ulcers etc.

Many factors.: Many factors go in to determining the success of a surgical weight loss procedure. The percent of excess body weight lost is important, however improvement and hopefully resolution of medical problems is also a significant factor in determining "success".