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Summary
This chapter discusses obesity and how it impacts on cardiovascular health and disease. Global prevalence of obesity has increased considerably over the past 30 years, impacting profoundly on morbidity, mortality, and healthcare costs. In the majority of individuals, susceptibility to this chronic disease depends on the inheritance of multiple genes, each conferring a very small relative risk; monogenic forms of obesity are rare. Lifestyle factors—including dietary patterns, physical activity, stress, sleep hygiene, and circadian rhythms—also have important roles in the development of obesity. Direct effects of the excess adipose tissue on other organ systems contribute to increased cardiovascular risk in obese individuals (see summary figure). The adverse health effects of excess adiposity manifest by the development of weight-related complications and the emergence of risk factors for those complications. In obese individuals, pathophysiological adaptations (such as in the hypothalamic regulation of appetite) make it challenging to reduce adiposity and maintain any weight loss. Recommended therapeutic strategies for obese individuals involve lifestyle intervention (including dietary changes, increases in physical activity, and behavioural therapy), pharmacotherapy, and bariatric surgery. Weight loss reduces risk of type 2 diabetes mellitus, lowers blood pressure, and results in lower triglyceride and LDL cholesterol levels and higher HDL cholesterol levels.
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Prevalence of obesity has increased sharply worldwide over the past 30 years.1 Globally, the proportion of adults with a body mass index (BMI) of 25 kg/m2 or greater increased between 1980 and 2013 from 28.8% to 36.9% in men, and from 29.8% to 38.0% in women.2 Prevalence has increased substantially in children and adolescents in developed countries to the point where 23.8% of boys and 22.6% of girls were overweight or obese in 2013.2 In the United States, data from the National Health and Nutrition Examination Survey (NHANES) show that roughly two out of three US adults are overweight or obese, more than one-third are obese, and 17% of children are obese.3,4 This has created a global health crisis with a profound impact on morbidity, mortality, and healthcare costs largely attributable to weight-related complications.
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In recent years, accumulating scientific evidence has confirmed that obesity is a chronic disease with interacting genetic, environmental, and behavioral determinants resulting in serious complications.5,6 In addition, exciting advances have occurred in all three treatment modalities for obesity: lifestyle intervention; pharmacotherapy; and weight-loss procedures, including bariatric surgery.6,7,8,9,10 Clinical trials have established the efficacy of lifestyle and behavioral interventions in the treatment of obesity, and refinements in surgical approaches and improved preoperative and postoperative care have improved outcomes of bariatric surgery. Importantly, there are now five weight-loss medications approved by the US Food and Drug Administration (FDA) for chronic management.6,7,8,9 These new therapeutic tools together with advances in our ...