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In the past 25 years, the prevalence of obesity (defined as a body mass index [BMI] of >30 kg/m2 ) has increased considerably in both sexes, all age categories and ethnic groups worldwide [1,2]. BMI, calculated as body weight in kilograms divided by the square of height in meters (kg/m2 ), is widely accepted as a surrogate method to define and quantify obesity as it relates to disease burden [3]. Obesity is defined as having a BMI of 30 kg/m2 or more, whereas adults with BMI between 25-29.9 kg/m2 are considered to be overweight [4]. Using these criteria, approximately a third of the US adult population is considered to be obese, and two out of three adults are considered at least overweight [2]. Whereas there are somewhat conflicting reports regarding the annual number of deaths attributable to overweight and obesity, there is considerable evidence showing that obesity increases the risk for Type 2 diabetes, coronary heart disease (CHD), hypertension (HTN), and several other significant diseases including cancer [5]. There is growing evidence that abdominal adiposity is a much stronger predictor of significant cardiovascular and metabolic diseases and associated mortality than BMI, particularly in Asian populations [6,7].
Since the risk of mortality from all causes worsens with increasing severity of obesity [8], clinicians should advise patients with BMI of 30 or more to lose weight, with special attention to those with class II (BMI 35.0-39.9) and III (BMI ≥40) obesity. In addition, weight reduction is indicated for overweight (BMI ≥25) and obese patients who have established CHD, family history of premature CHD, Type 2 diabetes, hypertension HTN, hypercholesterolemia, obstructive sleep apnea, osteoarthritis, and other illnesses that are known to improve to some degree with weight loss [4]. In general, 5-10% weight loss leads to improvements in blood pressure, glycemic measures and lipid profile in overweight and obese individuals. Weight reduction is also associated with improved cardiorespiratory fitness, mobility and health-related quality of life [4].
Antiobesity drugs are generally not regarded as first-choice interventions to achieve weight reduction. Guidelines from policymakers and consensus panels typically recommend lifestyle modification (caloric reduction combined with increased physical activity) as the initial intervention. Nevertheless, antiobesity drugs are regarded as suitable for patients with a BMI above...