Recent research has suggested that different groups of people stand to gain in different ways from obesity treatment.
Published in the JAMA journal, the study looked at 850 veterans who underwent obesity treatment between 2000 and 2006.
A control group were also monitored, who had an average age of 54.7 and an average Body Mass Index (BMI) or 42.
The veterans, meanwhile, had an average age of 49.5 years and a BMI of 47.4.
A total of 1.29 per cent of the surgical cases died within 30 days of surgery, but once six years had passed, a mortality rate of 6.8 per cent was recorded in this group.
Meanwhile, the control group had a mortality rate of 15.2 per cent after this time.
However, further analysis concluded that the surgery was not significantly associated with reduced mortality when propensity-match patients were looked at.
The study's authors noted: "Our results highlight the importance of statistical adjustment and careful selection of surgical and nonsurgical cohorts, particularly during evaluation of bariatric surgery according to administrative data."