University of California San Francisco researchers led by Dr Guilherme Campos also found gastric bypass improved quality of life and increased resolution of diabetes, compared with banding.
Patients undergoing gastric bypass surgery lose 60 per cent of weight on average, but morbidity is high and about one patient in 500 dies as a result of surgery.
The researchers said gastric banding has been touted as a less invasive and safer option than gastric bypass, but studies have suggested it may not be as effective in the long term.
Moreover, few studies have undertaken head-to-head comparisons of the efficacy and safety of the two procedures.
In the trial, researchers paired 100 morbidly obese patients treated with laparoscopic gastric bypass surgery with the same number who underwent laparoscopic gastric banding. Patients were matched based on sex, race, age, initial BMI and presence of diabetes.
Gastric bypass had a similar overall rate of complications to gastric banding and with a lower rate of re-operations.
After one year, patients who underwent gastric bypass surgery dropped 16 BMI points on average, compared with nine for those treated with gastric banding. Patients who underwent gastric bypass surgery also reported better quality of life after one year.
The researchers said the reduction in diabetes due to gastric bypass surgery may result from the rearrangement of the GI tract affecting secretion of hormones for glucose metabolism.
They concluded: 'This information should be provided when discussing bariatric surgical options with patients.'