Last Updated 3 September 2015
In the simplest of terms, obesity is the result of an imbalance in energy intake versus expenditure, leading to excess energy stores in the form of body fat (adipose tissue). The complex underlying signaling mechanisms that influence food intake and energy expenditure work in unity to maintain adiposity, even if body weight is pathogenically high. The evidence demonstrating the serious physical, economic, and societal effects of obesity is growing, which has resulted in more-concerted efforts to confront this important public health issue. Lifestyle modifications, such as diet and exercise, are the cornerstone of obesity management, but have limited efficacy. Bariatric surgery is by far the most effective treatment for obesity, but historically it has been restricted to severely obese patients. Pharmacotherapy aims to provide additional weight loss for those patients for whom diet and exercise is insufficient and where surgery is not suitable or affordable. However, the body’s innate predisposition to retain adipose tissue makes weight loss through pharmacological intervention very challenging. Moreover, several high-profile withdrawals of marketed antiobesity agents have occurred owing to serious adverse events. Understandably, physicians remain cautious about novel weight-loss therapies. Entrenched attitudes about obesity being a lifestyle disorder, limited therapeutic options, and a challenging reimbursement environment in most markets have contributed to low diagnosis and drug-treatment rates. At first glance, the commercial opportunity of the obesity market looks considerable: a large number of prevalent cases with limited treatment options. However, it is the potential magnitude of the market that is one of its chief constraints. Healthcare budgets are unlikely to be able to finance wide reimbursement of obesity drugs, because of the number of eligible recipients. On the other hand, the long-term burden of the comorbidities and complications of untreated obesity will place an increasing drain on healthcare resources. Moreover, if access to obesity drugs is too difficult, there will be little incentive for pharmaceutical companies to invest in research and development in this field, which will only compound the problem. Nevertheless, we do expect the market to expand, driven by greater recognition of the medical, social, and economic implications of obesity, and several emerging therapies, including the first agents to be approved in Europe for many years.