The study, which looked at the long-term effectiveness of anti-obesity medications, found that three drugs recommended for long-term use – orlistat, sibutramine and rimonabant, reduced weight by less than 5kg (11 pounds). This equated to a loss of less than 5% of total body weight. Guidelines from the National Institute for Clinical Excellence recommend stopping the use of anti-obesity drugs if 5% of total body weight is not lost after three months
Current UK guidelines recommend using drug therapy in addition to making lifestyle changes if a patient has a body mass index of greater than 30.
The Canadian researchers reviewed the evidence from thirty placebo-controlled trials where adults took anti-obesity drugs for a year or longer. The mean weight of the volunteers in all of the trials was 100kg (15.7 stone). The mean body mass index levels were 35 â€“ 36.
The health benefits associated with taking the drugs varied. For example, orlistat reduced the incidence of diabetes in one trial and all three drugs lowered patients levels of certain types of cholesterol. Adverse effects were recorded with all three drugs, in particular, rimonabant increased the risk of mood disorders such as depression or anxiety.