Chapter 3: Weight Management 47 • Fat cell theory. This theory says that obese individuals have too many fat cells. People with an above-average number of fat cells may have been born with them or developed them over time as a result of overeating. It is believed that, through proper diet and exercise, individuals can decrease the size of fat cells but not the number. • Set point theory. This theory says that obese individuals are genetically predisposed to carry a certain amount of weight. This predisposition is set and determined by the hypothalamus. This theory also states that losing weight, and keeping it off, is often times hard to do because the body strives to get back to its predisposed set point. In order to lose weight, and keep it off, the individual must somehow change their set point. • Glandular disorder theory. This theory says that hypothyroidism, a condition in which the body does not produce enough thyroid hormone, is responsible for excessive weight gain and obesity. However, research has shown that overt hypothyroidism only causes modest weight gain (Sanyal & Raychaudhuri, 2016). Additionally, thyroid hormone treatment generally does not lead to significant weight loss. • Positive energy balance theory. This theory says that weight gain occurs when caloric intake exceeds energy expenditure. In essence, the relationship between calories consumed and calories burned can result in one of the following three scenarios: o Weight gain = calories consumed > calories burned o Weight loss = calories consumed < calories burned o Maintain weight = calories consumed = calories burned Other Factors Contributing to Weight Gain There are several additional factors believed to contribute to weight gain and obesity to include (Thygerson & Thygerson, 2016): • Genetics. More than 400 different genes are implicated in the development of obesity. Genes can contribute to obesity in several ways such as affecting appetite, satiety, metabolism, food cravings, fat distribution, and stress eating. • Diseases. Certain illnesses affect the endocrine glands which can in turn cause weight gain. Some of these illnesses include hypothyroidism, polycystic ovarian syndrome and tumors on the pituitary gland, adrenal glands and/or pancreas.
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