Special Populations: Obesity
Obesity is a chronic condition defined by excess body fat. Body fat is necessary for storing energy, heat insulation, limb and organ protection, and many other important functions. The normal amount of body fat in women is 25%-30% and 18%-23% in men. Women with over 30% body fat and men with over 25% body fat are considered clinically obese. Obesity can start from the moment of conception. The nutritional status of the mother, the choice of breast or formula milk and the volume of milk provided, can set the weight trajectory of an infant. As the infant grows into a child, the food choices, quality of food and heredity help determine the likelihood of that child becoming obese. These factors may also play a significant role in the difficulty level of avoiding obesity as a teenager or adult.
The prevalence of obesity is an epidemic in the United States. Data from the most recent studies show the obesity rate in adult men to be 31% in 2004, and growing to 33% in 2006, a small but not statistically significant change. Among adult women, the rates are a bit higher, at 33% in 2004 and 35% in 2006. The prevalence of obesity in children has increased markedly, with approximately 20%-25% of children either overweight or obese. Obesity affects people of all nationalities, as the incidence of obesity nearly doubled form 1991 to 1998, worldwide. In the United States, forty percent of the adult population is obese.
Obesity increases the risk of many diseases and health conditions:
Coronary heart disease
Type 2 diabetes
Cancers (endometrial, breast, and colon)
Hypertension (high blood pressure)
Liver and Gallbladder disease
Sleep apnea and respiratory problems
Obesity contributing factors:
Genetics. The likelihood of obesity increases if one parent is obese. The ability to regulate or metabolize fat often depends on genetic hormones. Leptin deficiency is one example. Leptin is a hormone produced in fat cells, and also in the placenta. Leptin (Latin for thin) is a protein hormone with important effects in regulating body weight and metabolism. It controls body weight by signaling the brain to eat less food when body fat stores are at capacity. If, for any reason, the body cannot produce enough leptin or leptin cannot signal the brain to eat less, this control is lost and a person will overeat.
Physical inactivity. Sedentary people burn fewer calories than people who are regularly active. Annually, physical inactivity causes two million deaths worldwide. Globally, it is estimated to cause about 10-16% of cases each of breast cancer, colon cancers, and diabetes, and about 22% of heart disease.
Frequency of eating. The frequency of eating and its effects on obesity are not completely understood. It is clear that some overweight people eat less often than people with normal weight. It is understood that people who eat smaller meals throughout the day have lower cholesterol levels and lower blood sugar levels than people who eat less frequently (two or three times a day). One possible explanation is that small frequent meals produce stable insulin levels, whereas large meals can cause insulin spikes and slow metabolism. Eating less frequently slows metabolism, forcing the body to store more of the food eaten, including cholesterol and fat. Eating more frequently speeds metabolism and helps burn calories.
Overeating. Overeating leads to weight gain. It’s a simple formula of calories in and calories out. If a person consumes more calories than he/she expends, the result will be weight gain. Foods high in fat or sugar exacerbate the problem. A diet high in simple carbohydrates increases blood glucose levels, which in turn, stimulates insulin release by the pancreas. Insulin promotes the growth of fat tissue and can cause weight gain. Simple carbohydrates absorb more rapidly into the blood stream than complex carbohydrates, and therefore cause a more pronounced insulin release. Overtime, increased insulin release can contribute to weight gain.
Psychological factors. One’s emotional state can influence how and what one eats. Many people use food to comfort them when feeling sad, angry, bored or anxious. This type of eating is referred to as binge eating. Forty percent of those who seek treatment for serious weight problems have difficulties with binge eating. Episodes of binge eating also occur in bulimia nervosa, an eating disorder. After an episode of binge eating, persons with bulimia regularly vomit, engage in strenuous exercise, consume diet pills and/or diuretics.
Medications. Medications associated with weight gain include certain antidepressants, anticonvulsants, diabetes medications and certain hormones such as oral contraceptives. Weight gain may also be a side effect of some high blood pressure medications and antihistamines.