Bariatric treatments for adult obesity - Institute of Health Economics

• young adults who have not reached full growth;• adults who have a naturally lean body build;• adults who have a highly muscular body;• adults who are very tall or very short;• elderly adults (those aged 65 and over);• pregnant women;• certain ethnic groups.The latest research indicates that, when considering the health risks associated with obesity, it isimportant to determine both the amount of fat an individual has and the location of fat stores in thebody. 1,3,5,6,10,19,20,22,24,25,27,33-35 Excess abdominal fat (also referred to as central adiposity or abdominalobesity) is recognized as an important, independent risk factor that appears to drive many of theendocrine, cardiovascular, and malignant consequences of obesity.The amount of abdominal fat can be assessed by waist circumference and waist-to-hip ratiomeasurements. 1-3,5,6,10,19,20,22,24-28,33-35 In clinical practice, waist circumference, which is directlyassociated with abdominal fat content, is more frequently used as an index of abdominal fat than thewaist-to-hip ratio, which is more difficult to measure. Men with waist circumferences equal to orgreater than 102 cm (40 inches) and women with a waist circumference equal to or greater than 88cm (35 inches) are considered at increased risk for cardiovascular disease and a range of otherconditions, such as T2DM and sleep disorders.However, the established waist circumference cut-off points have not been validated for their abilityto discriminate clinical events and are likely to differ in various subgroups (men versus women,different adult age groups, and different ethnic populations). Another limitation to using waistcircumference measurements is their inability to distinguish visceral adipose tissue from overlyingsubcutaneous adiposity. 1-3,5,6,13,20,22,24,26,27,34,36 Measuring waist circumference is most useful inindividuals with a BMI < 35 kg/m 2 .Pathogenesis of obesityThe cause of obesity is complex and multifactorial and may differ from one individual toanother. 1,3,4,6,9,11,15,19,20,23,24,31,32,37-45 At the simplest level, obesity results from long-term energyimbalance and fat stores due to the interaction of energy intake and energy output or expenditure.However, complex interactions between genetics, hormones, and various behavioural,socioeconomic, cultural, and other environmental factors are involved in the regulation of energybalance and fat stores.It is presumed that 20% to 75% of the variability of body weight and composition within apopulation is explained by genetics. 23,24,31,42,44-46 Genetic factors can either play a major role in thepathogenesis of obesity or can enhance susceptibility to its development. 23,24,31,38,42 In somepopulations, such as in the Canadian Aboriginal population, genetics may play a more predominantrole in the pathogenesis of obesity and the gene-environment interaction may be particularlystrong. 31,38 Although multiple candidate genes have been implicated in the pathogenesis ofobesity, 23,24,38,42,44 the findings are inconsistent. 24 The rapidly occurring changes in obesity prevalenceover the past 30 years are highly unlikely to be explained only by genetic changes.Bariatric treatments for adult obesity – March 2012 5