About one third of the US population and one quarter of the UK population are obese, with increased risks of hypertension, dyslipidaemia, diabetes, cardiovascular disease, osteoarthritis, and some cancers. Fewer than 10% of overweight or obese adults aged 40 to 49 years revert to a normal body weight after 4 years. Nearly 5 million US adults used prescription weight-loss medication between 1996 and 1998, but one quarter of all users were not overweight.
Methods and outcomes
We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of drug treatments in adults with obesity? What are the effects of bariatric surgery in adults with morbid obesity? We searched: Medline, Embase, The Cochrane Library, and other important databases up to September 2010 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).
We found 39 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.
In this systematic review, we present information relating to the effectiveness and safety of the following interventions: bariatric surgery versus medical interventions, biliopancreatic diversion, diethylpropion, gastric bypass, gastric banding, mazindol, orlistat (alone and in combination with sibutramine), phentermine, sibutramine (alone and in combination with orlistat), sleeve gastrectomy, and vertical banded gastroplasty.
About one third of the US population and one quarter of the UK population are obese, with increased risks of hypertension, dyslipidaemia, diabetes, CVD, osteoarthritis, and some cancers.
Fewer than 10% of overweight or obese adults aged 40 to 49 years revert to a normal body weight after 4 years.Nearly 5 million US adults used prescription weight-loss medication between 1996 and 1998, but one quarter of all users were not overweight.
Orlistat, phentermine, and sibutramine may promote modest weight loss (an additional 1–7 kg lost) compared with placebo in obese adults having lifestyle interventions, but they can all cause adverse effects.
Sibutramine may be more effective at promoting weight loss compared with orlistat, although not in obese people with type 2 diabetes or hypertension.We don't know whether combining orlistat and sibutramine treatment leads to greater weight loss than with either treatment alone.We don't know whether diethylpropion and mazindol are effective at promoting weight loss in people with obesity.Orlistat has been associated with GI adverse effects.Phentermine has been associated with heart and lung problems.Sibutramine has been associated with cardiac arrhythmias and cardiac arrest. In January 2010, the European Medicines Agency suspended marketing authorisation of sibutramine in the European Union because of the increased risk of non-fatal myocardial infarctions and strokes.In October 2010, the FDA requested the withdrawal of sibutramine from the US market because of the increased risk of adverse cardiovascular events.Rimonabant has been associated with an increased risk of psychiatric disorders.
Bariatric surgery (gastric bypass, vertical banded gastroplasty, biliopancreatic diversion, or gastric banding) may increase weight loss compared with no surgery in people with morbid obesity.
Compared with each other, we don't know whether gastric bypass, vertical banded gastroplasty, biliopancreatic diversion, or gastric banding is the most effective surgery or the least harmful.
We don't know whether sleeve gastrectomy is effective. Bariatric surgery may result in loss of >20% of body weight, which may be largely maintained for 10 years.Operative and postoperative complications are common, and on average 0.28% of people die within 30 days of surgery. Mortality may be as high as 2% in some high-risk populations. However, surgery may reduce long-term mortality compared with no surgery.