Bariatric surgery to help the obese shed weight also reduces risks of cardiovascular disease, according to a review published on Wednesday in the specialist journal Heart.
Restrictive bands on the stomach or surgery to bypass part of the digestive tract are sometimes used to help morbidly obese patients lose weight when drugs or changes in diet and exercise fail.
Researchers at the Cleveland Clinic in Cleveland, Ohio, carried out a database trawl to pick out 73 previous studies, covering nearly 20,000 people, that detailed weight and other health issues before and after bariatric surgery.
After the operation, participants lost on average 54% of the excess weight they were carrying, a tally that ranged from 16 to 87%.
High blood pressure improved in 63% of patients, diabetes in 73% and blood cholesterol in 65% of them. Surgery led to improvements in the heart function.