In addition to helping obese patients drop pounds weight loss surgery can also improve their overall health, even if there is some risk for complications, according to a new study Reuters reported.

Researchers found that bariatric surgery, a variety of weight loss procedures performed on moderately to severely obese people, have improved patient's health by reversing the effects of obesity and the diseases related to it, such as diabetes, high blood pressure and sleep apnea.

"Bariatric surgery has become one of the safest intra-abdominal major procedures," Dr. Mitchell Roslin, chief of weight-loss surgery at Lenox Hill Hospital in New York City who was not involved in the study, told HealthDay.

Researchers wanted to examine the effectiveness and risks of bariatric surgery using up-to-date, comprehensive data and "appropriate meta-analytic techniques," according to the study.

For the review, researchers examined 164 studies conducted from 2003 to 2012, which included a total of 161,756 patients. Eighty percent of the patients were females and on average, they were 45 years old.

Before surgery, the patients' average body mass index (BMI) or measure of weight relative to height was nearly 46. Anyone with a BMI that is more than 35 is considered obese, while a BMI of 18.5 to 24.9 is considered normal

Patients' presurgery weight averaged 274 pounds. More than 25 percent of the patients had diabetes, nearly half had high blood pressure and almost 30 percent had high cholesterol. Seven percent had heart disease and 25 percent had sleep apnea.

Researchers saw a drop in the patients' BMI by an average of 12 to 17 points within five years after the surgery.

They also saw an improvement in their overall health as obesity-related diseases found in the patients improved significantly, Reuters reported. Between 86 percent and 92 percent of patients with diabetes experienced remission of the disease. The same happened for about 75 percent of those with high blood pressure.

Reuters reported that researchers saw high cholesterol and heart disease roll back at slightly lower rates, but sleep apnea disappeared or improved dramatically in more than 90 percent of those who had it pre-surgery.

"Weight loss surgery provides substantial effects on weight loss and improves obesity-related conditions in the majority of bariatric patients, although risks of complication, reoperation and mortality exist," Su-Shin Chang, review author and instructor in the division of public health services at the Washington University School of Medicine, told HealthDay.

Death rates were also lower than previously thought.

Reuters reported that death rates ranged from 0.08 within one month of surgery to 0.31 after 30 days. Complication rates ranged from 10 percent to 17 percent.

"Death rates are, in general, very low," Chang said.

Dr. Pratt Vemulapalli, director of bariatric surgery and an associate professor of surgery at the Montefiore Medical Center of the University Hospital for the Albert Einstein College of Medicine in New York, told Reuters said the most common procedures are the gastric bypass, the sleeve gastrectomy and, to a lesser extent, the adjustable gastric band.

Vemulapalli, who was not involved in the study, said there are currently about 200,000 weight loss procedures performed each year.

The report was published online Dec. 18 in the journal JAMA Surgery.