By Lisa Rapaport

(Reuters Health) - Five years after weight loss surgery, obese patients may regain many of the pounds they initially shed, a new study from Israel suggests.

While surgery remains more effective for lasting weight loss than alternatives such as dieting and exercising, said lead study author Dr. Andrei Keidar, the study findings suggest that doctors still have more to learn about which patients will get the most benefit from operations and what strategies can make the initial results stick.

"The first year after surgery is usually a honeymoon period that should be used for coining new habits, and the ones that don't do that regain weight," Keidar, a researcher at Tel Aviv University, said by email. "Don't take surgery as a panacea - beware of bad eating habits."

Keidar and colleagues followed 443 obese patients who had sleeve gastrectomy procedures to see how much weight they lost and whether they experienced improvements in other health problems tied to obesity such as diabetes, hypertension and high cholesterol.

After one year, the participants still in the study had lost 77% of their body weight on average, but they slid back toward to their original weight as time passed. At three years, they were still down by 70% of their original weight, and just 56% at five years.

About half of the patients with diabetes experienced complete remission after one year. In this, too, patients backslid over time, with just 38% in complete remission after three years and only 20% at five years.

Participants experienced significant reductions in low-density lipoprotein (LDL) cholesterol levels at one year and three years, but at five years the change was so small it might have been due to chance.

Roughly 46% of people with hypertension returned to a normal blood pressure at one year and at five years.

One shortcoming of the study is that many patients dropped out at each stage, leaving results for very few participants at five years, the researchers note in JAMA Surgery online August 5.

"There are still critical gaps in knowledge about the long-term (5 years and longer) results of bariatric surgery," Dr. Anita Courcoulas, author of an editorial accompanying the study and chief of bariatric surgery at the University of Pittsburgh Medical Center, said by email.

A separate study in the journal examined the effects of alcohol consumption after Roux-en-Y operations. Researchers found that after surgery, patients who drank the same amount they did before the operation experienced a much faster increase in blood alcohol levels, which were about twice as high as they would have been before surgery.

"Because blood alcohol levels are doubled after surgery, people could engage in risky drinking when drinking only moderate amounts of alcohol," lead study author Marta Yanina Pepino of the University of Washington School of Medicine in Seattle, said by email.

This issue, as well as the potential to regain some weight initially lost, shouldn't deter obese patients from considering operations, said Dr. John Morton, president of the American Society for Metabolic and Bariatric Surgery (ASMBS)and head of bariatric surgery at Stanford University School of Medicine in California.

"You get meaningful health changes with just a 5% weight loss, so losing 50% after five years is still a heck of a lot of improvement," he said. "These are the sickest of the sick who seek out bariatric surgery, and the vast majority of patients benefit."

SOURCE: http://bit.ly/1dDjZYQ and http://bit.ly/1JM6dI6

JAMA Surg 2015.