Five years after undergoing weight loss surgery, obese patients are likely to begin to regain the pounds they initially shed, a new study has warned.
Experts do not deny bariatric operations are more effective to secure lasting weight loss than dieting and exercise alone.
But, they warn their findings suggest doctors need to learn more about which patients will get the most benefit from the procedures.
Futhermore the team at Tel Aviv University in Israel said medics should focus on developing post-op strategies for patients to help their initial weight loss last.
Dr Andrei Keidar, who led the study, told Reuters Health: ‘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.
‘Don’t take surgery as a panacea – beware of bad eating habits.’
Across the world, 1.9 billion adults are deemed overweight or obese, according to the World Health Organisation.
Countless studies have proven obesity increases the risk of heart disease, diabetes, joint disorders and certain types of cancer.
In recent years, surgery to achieve weight loss has become more popular.
But the operations are not without risk, with some patients becoming malnourished as a result.
In the US alone, around 180,000 people undergo weight loss surgery each year, figures from the American Society for Metabolic and Bariatric Surgery reveal.
The most common operation is known as a sleeve gastrectomy, which reduces the stomach to the size of a banana.
That is followed by a procedure known as Roux-en-Y, which creates an even smaller stomach pouch.
Dr Keidar and colleagues followed 443 obese patients who had sleeve gastrectomy operations to see how much weight they lost, and whether they saw improvements in other health conditions, including diabetes, high blood pressure and high cholesterol.
After one year, participants still in the study had lost 77 per cent of their body weight, on average.
But as time wore on, they gradually increased in weight, creeping back towards their original weigh in.
At three years, they were still down by 70 per cent of their original weight.
But by five years just 56 per cent of participants still weighed less than before their operation.
About half of patients with diabetes experienced complete remission after one year.
But, as with weight loss, these patients also saw their diabetes return over time.
Just 38 per cent were in complete remission after three years, and 20 per cent at five years.
But at five years the change was so small, researchers concluded it could have been due to chance.
Roughly 46 per cent 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.
Dr Anita Courcoulas, chief of bariatric surgery at the University of Pittsburgh Medical Center, who wrote an accompanying editorial, said: ‘There are still critical gaps in knowledge about the long-term results of bariatric surgery.’
A separate study, also published 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 as before the operation, experienced a much faster increase in their blood alcohol level.
Lead study author, Dr Marta Yanina Pepino, of the Washington University School of Medicine in St Louis, said: ‘Because blood alcohol levels are doubled after surgery, people could engage in risky drinking when drinking only moderate amounts of alcohol.’
Dr John Morton, president of the American Society for Metabolic and Bariatric Surgery and head of bariatric surgery at Stanford University School of Medicine, said these studies should not deter obese patients from considering surgery.
He said: ‘You get meaningful health changes with just a five per cent weight loss, so losing 50 per cent after five years is still a heck of a lot of improvement.