Obesity
Pathological excess of neutral fats (triglycerides) due to increased adipose tissue in the body. In obesity, body mass index (BMI) is greater than 30 kg/m2. Obesity can be primary or secondary. Primary obesity is associated with increased food intake and decreased energy expenditure. Secondary obesity is a syndrome that occurs in various endocrinopathies. Obesity can be central (visceral) or peripheral. In central obesity, fats are deposited between internal organs and within the organs themselves. These individuals have a protruding abdomen, hence this obesity is also called “apple” type obesity. This is the most dangerous obesity because adipose tissue cells secrete substances that cause metabolic syndrome. This obesity is associated with disturbances in the neuroendocrine signaling axis – hypothalamus-pituitary-adrenal function. In the case of peripheral obesity, fats mostly accumulate under the skin, subcutaneously. This is called “pear” type obesity. It is less dangerous but still undesirable. The risk of obese people developing heart and vascular diseases, hypertension, type II diabetes, gallbladder, joint diseases, and certain forms of cancer increases. The main factors contributing to the development of obesity are appetite, amount of food consumed, food composition, rate of metabolism of food substances, psychological factors, and heredity. In the adipose tissue triglycerides of a normal adult human, about 150,000 kcal of energy is stored, in proteins and amino acids – 24,000 kcal, in glucose and glycogen – about 1000 kcal. To maintain vital body processes (synthesis of new substances, muscle work, body temperature maintenance, etc.), about 2500 kcal per day is needed. The main chain regulating energy homeostasis and body mass stability is the hypothalamus in the brain. In its nuclei, there are feeding centers controlling hunger and satiety. There is a synaptic connection between hunger and satiety centers transmitting inhibitory impulses. The feeling of satiety depends on the filling of the digestive tract, the amount of protein in food, and cytokines released by adipose tissue – peptide hormones. The feeling of hunger occurs when external feeding ends and fat reserves stored in adipocytes begin to be used, i.e., when the body starts using metabolic energy reserves. Obesity begins when fat tissue starts to favor fat synthesis (lipogenesis) over fat breakdown (lipolysis), as adipocytes constantly undergo a balance between lipogenesis and lipolysis processes.
Source | Glossary of Most Commonly Used Biomedical Terms and Concepts | Lithuanian University of Health Sciences | Academician Professor Antanas Praškevičius, Professor Laima Ivanovienė