Anti obesity drugs are no substitute for a healthy diet and lifestyle for those who want to lose weight, scientists in Canada have found.
Researchers at the University of Alberta reviewed the evidence from thirty trials involving nearly 20,000 people who took one of three anti-obesity drugs -- orlistat, sibutramine or rimonabant -- for a year or longer.
They found that in many cases the pills achieved little in terms of weight loss, reported the online edition of BBC News.
Patients taking anti-obesity drugs lost only "modest" amounts of weight and many remained significantly obese or overweight, the researchers found.
All the volunteers in the trials were deemed obese and weighed an average of 100 kg. Orlistat reduced weight by 2.9 kg, sibutramine by 4.2 kg and rimonabant by 4.7 kg.
However, patients taking the weight loss drugs were significantly more likely to achieve five to 10 per cent of weight loss compared to those who took a placebo, the scientists said.
But a separate study published in The Lancet medical journal found patients given rimonabant were at increased risk of severe psychiatric problems.