44 Chapter 3: Weight Management • 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: • Weight gain = calories consumed > calories burned • Weight loss = calories consumed < calories burned • 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. • Drugs. Several drugs can increase appetite and/or slow metabolism thereby causing weight gain as a side effect. Some of these drugs include: corticosteroids, estrogen and progesterone, specific anti-cancer medications, antidepressants and certain psychiatric drugs. • Socioeconomic status. Individuals who are below-average income, less-educated and/ or unemployed have a higher incidence of obesity. • Age. Fat mass tends to increase with age through adulthood and eventually decline when elderly. • Gender. Obesity is more prevalent in women than in men. • Ethnicity. Obesity is more prevalent in African-American, Hispanic, Native American and Pacific Islander populations. Although the exact causes for these disparities are not fully understood, it is believed to be due, at least in part, to differences in social and economic advantage related to ethnicity (Krueger & Reither, 2015).
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