Chapter 39: Alterations in Nutritional Status

Energy balance is maintained by regulating intake and expenditure, the latter involving the Basal Metabolic Rate (BMR) and various forms of thermogenesis, including diet-induced, exercise-induced, and Nonexercise Activity Thermogenesis (NEAT). Adipose tissue is highlighted not only as the primary energy storage site but also as an active endocrine organ that secretes adipokines like leptin, which signals satiety to the hypothalamus and regulates energy consumption. Nutritional needs are addressed through guidelines like the Dietary Reference Intakes (DRIs), covering requirements for macronutrients, essential vitamins (fat- and water-soluble), and minerals. The concept of overnutrition focuses on overweight and obesity, which are classified using the Body Mass Index (BMI). The chapter details the causes, significant health risks associated with central or upper body obesity (visceral fat accumulation), and multidisciplinary treatment approaches including diet, behavior modification, pharmacotherapy, and bariatric surgery. Conversely, undernutrition and starvation are examined, defining Protein–Energy Malnutrition (PEM) by contrasting marasmus (deficiency in both calories and protein, leading to wasting) and kwashiorkor (primarily protein deficiency, associated with edema). Finally, the chapter analyzes common eating disorders such as Anorexia Nervosa (AN), characterized by low body weight and distorted image; Bulimia Nervosa (BN), defined by recurrent binging and compensatory behaviors; and Binge Eating Disorder (BED).