FRIDAY, Feb. 28, 2020 (HealthDay News) -- Weight-loss surgery is as effective for people who became obese before age 20 as for older patients, new research shows.

For the study, researchers from the University of Gothenburg, in Sweden, analyzed data from just over 4,000 obese adults. Half had undergone weight-loss surgery, half did not. They were divided into three groups based on their body mass index (BMI) at age 20: normal, overweight, and obese. (BMI is an estimate of body fat based on height and weight.)

The results came as somewhat of a surprise to the researchers. They expected that weight-loss surgery would have fewer health benefits for patients who were already obese by age 20.

"But it wasn't like that," said study co-author Johanna Andersson-Assarsson, a researcher in the department of molecular and clinical medicine.

"On the contrary, the group with obesity at age 20 lost a little bit more weight after the operation, and there was no difference in effects on diabetes or its complications, cardiovascular disease or cancer, compared with individuals who developed obesity later in life," she said in a university news release.

Early treatment is often advantageous for many diseases. But some have suspected that weight-loss surgery (also called "bariatric surgery") would be less effective in individuals with early-onset obesity due to extended time with the condition.

"Here, we show that's not the case. And we think it's important that this information reaches people considering bariatric surgery for obesity, and also health professionals who treat patients with obesity," Andersson-Assarsson said.

The findings were recently published in the journal Diabetes Care.

More information

The U.S. Centers for Disease Control and Prevention has more on obesity.