Well, there are a number of studies that show that at 2 years at most 20%
of obese persons who started on a diet plan, any plan, have maintained
weight reduction. Following gastric bypass, that number is around 80-85%,
and for SRVG or more limitted operations it is around 66%. Although there
are no good RCT's, the differences are so large, that they do form good
evidence that maintaining weight reduction is much better with the
operation than without it.
Several problems are clearly ameliorated by bariatric surgery: Diabetes &
HTN becomes easier to control, or disappear completely. Chronic Joint
disease is better tolerated, and sleep apnea is frequently controlled.
I think that barriatric surgery should be offered to obese patients with
any of the above problems.