In 2005, obesity rate was declared 396 million worldwide, which has been doubled in the last 20 years (compared with 1985). Obesity has a strong correlation with a pool of comorbidities and consequences. Although many modules, including behavioural approach and medications have presented particular short-term unreliable methods to reduce and control the body weight in morbid obesity, only 5 - 10% of weight loss was achieved, which is usually regained overtime, compared with 50 - 75% success rate in bariatric surgery.

This retrospective study tried to monitor weight loss after LRYGB and LSG in morbid obese patients referred to a known center in Tehran through a one-year follow up.

Participants were selected regarding the U.S. National Institute of Health (NIH) guidelines, which indicates BMI > 40 kg/m² alone, or BMI > 35 kg/m² in addition to comorbidities and failure of non-surgical attempts to control their weight. They were visited at points of one, three, six, and 12 months postoperatively to collect information about weight loss, BMI, and complications in addition to percent excess weight loss (EWL%). The percentage of failure was computed to the proportion of patients who had EWL% < 25 to the total number of operated patients in a year.

Significant decrease in BMI and weight were achieved in all postoperative visits (for all of them, P value < 0.0001), while no significant difference was found in which the parameters between two studied procedures were in this regard.

To sum up, LRYGB and LSG deserve an overall preference not only in current study, but also in the majority of performances up to now. Nevertheless it is urgent the relevant studies to confirm the preference or improve this kind of bariatric surgery in order to diminish complications as far as possible.