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Figure 1. Endocrinologic etiologies of obesity and related pathophysiology. PHP: Pseudohypopparathryoidism.
(Figure omitted. See article PDF.)
During the past few decades, prevalence of obesity has dramatically increased in the Western world, including the USA where obesity has currently reached epidemic proportions. A comparison of data from two National Health and Nutrition Examination Surveys (NHANES) has shown that among US adults, the prevalence of obesity increased from 15% (in the 1976--1980 survey) to 32.9% (in the 2003--2004 survey) [1]. Data from the 2003--2004 survey estimate that approximately 66% of US adults are overweight or obese and 17.1% of US children and adolescents are also overweight [1]. This sharp increase in the prevalence of obesity correlates with a proportional increase in obesity-associated comorbidities, such as Type 2 diabetes, hypertension and cardiovascular disease (CVD) [2], and a significant rise in healthcare costs related to obesity [3]. The economic burden of obesity in the USA was estimated to be US$117 billion in 1998, with obesity accounting for approximately 5.7% of the US National Health expenditure [3].
The relatively rapid and dramatic increase in the prevalence of obesity has been largely attributed to a changing lifestyle that promotes increased caloric intake and reduced physical activity. A high-fat diet, excessive consumption of sugar-sweetened beverages and increased fast food intake might all contribute to the continuing increase in prevalence of obesity [4].
Although most cases of weight gain are indeed related to increased caloric intake and sedentary lifestyle, obesity can also be secondary to known and possibly treatable neuroendocrine or genetic disorders that affect appetite, metabolism, energy balance and fat distribution (Box 1). Although rare, these conditions should be recognized by physicians and specific therapeutic strategies should be planned in conjunction with diet and exercise.
In this review, we provide the readers with a general overview of the secondary causes of obesity, highlighting the pathophysiology, the clinical diagnosis and the therapeutic options of each disorder.
Obesity is a state of excessive body weight associated with adverse health risks such as diabetes, hypertension, hyperlipidemia and coronary artery disease. In 1997 and 1998, The WHO and the National Heart Lung and Blood Institute of the National Institute of Health advocated the use of a specific BMI threshold of 30 to diagnose obesity and...