Thyroid and Obesity: An Intriguing Relationship

Obesity is one of the most important health risks of our time. The prevalence of obesity has increased worldwide since the mid 1970s. According to the National Health and Nutrition Examination Survey, obesity affected 32.2% of adults in 2003–2004 and reached a peak in subjects in the fifth decade of life (1). Obesity is associated with an increased risk of diabetes, dyslipidemia, kidney disease, cardiovascular disease, all-cause mortality, and cancer (1). Thus, severe obesity is an important cause of premature mortality among middle-aged adults (2). Moreover, obesity, especially central obesity, is linked to many endocrine abnormalities (3), including thyroid dysfunction (4). This is not surprising because T3 regulates energy metabolism and thermogenesis and plays a critical role in glucose and lipid metabolism, food intake, and the oxidation of fatty acids (4).