What are the causes of obesity?
Obesity results from an impaired energy balance. When energy intake is higher than its consumption, energy balance deteriorates. Every person has a certain rate of basal metabolism. In other words, the cells in the human body consume a certain amount of energy to maintain their normal functions. This amount of energy is about 25-35 kcal/kg. Additionally, we need extra energy consumption to perform our normal physical activities. We meet the energy needs with food intake. This equation needs to be in balance. If the amount of energy we obtain from food increases and the energy we spend on exercising decreases, the body starts to accumulate the excess energy in the form of fat, developing obesity.
Obesity is inevitable when hyperphagia and especially high-fat food intake occur. These individuals consuming high-fat foods feel an incessant urge to eat with no feelings of satiety, resulting in excessive calorie intake and storage.
Total consumption is the second component of the energy balance, occurring in three ways. These include the basal metabolic rate, dietary thermogenesis, and physical activity.
Approximately 60% of total energy consumption in sedentary adults accounts for the basal metabolic rate. Thermogenesis and physical activity account for 10% and 30% of the energy consumption, respectively. The basal metabolic rate is related to lean body mass. Both the adipose tissue and lean body mass are high in obese individuals, resulting in a high basal metabolic rate almost all the time.
Total energy consumption increases in patients performing extreme physical activities. Of this energy consumption; 50% is spent on exercising and physical activities, while the dietary thermogenesis remains at the 10% level with a basal metabolic rate of 40%.
Various behavioral changes and physiological, psychological, genetic, medical, endocrinologic, and therapeutic factors are involved in developing obesity.
Reductions in physical activity impending with advancing age, a sedentary lifestyle, stopping workouts due to job-related changes or social influences, preferring to stay at home and preferring to watch television, as well as maintaining irregular dietary habits including having snacks between meals, frequent consumption of energy-rich food and drinks, especially eating foods rich in fat content, and alcohol use will eventually lead to obesity.
Physiologically, the tendency to gain weight develops during pregnancy, in the prenatal period, at the ages of 5-7 years, in adolescence, early adulthood, and menopause.
Psychological factors, too, are among the factors causing obesity. It is especially more common in western societies. The relationship of obesity to emotional stress, depression, and mental disorders is well-known. These conditions result in behavioral disorders, negatively affecting dietary habits.
Of the endocrinological diseases; hypothyroidism, Cushing Syndrome, type 2 diabetes, hypothalamic tumors, and some rare genetic syndromes are among the causes of obesity.
Therapeutic drugs can sometimes cause obesity. These are tricyclic antidepressants, sulfonylureas, steroid contraceptives, corticosteroids, and the antiepileptic drug valproate.
Besides all of these factors, familial predisposition is naturally a major factor involved in developing obesity.