Weight Management Chapter 14

Health Risks Associated with Excess Body Fat Obesity Is associated with: Unhealthy cholesterol and TG levels Impaired heart function CVD Hypertension Cancer Impaired immune function Gallbladder and kidney disease Skin problems Impotence, sleep disorder back pain, arthritis Type II diabetes (strong association)

Body Composition Visceral Fat Subcutaneous Fat Percent Body Fat Fat surrounding organs (within abdomen) Subcutaneous Fat Fat just below the skin Percent Body Fat Definition: Proportion of the body’s total weight that is fat

Evaluating Body Weight and Body Composition Methods for Evaluating Obesity Body Mass Index (BMI) Calculated by the following equation: Weight in pounds X 703 / Height in inches (squared) Under 18.5 = underweight 18.6 - 24.9 = healthy 25-30 =overweight Over 30 = obese

Methods of Determining Percent Body Fat Hydrostatic (underwater) weighing Most accurate Lean tissue is more dense than water; Fat tissue is less dense than water. Therefore a person with more body fat will weigh less underwater and be more buoyant Skinfold measurements Measures thickness of fat under the skin Electrical Impedance Analysis Electricity prefers lean tissue Scanning procedures CT scan, MRI, Dual-energy X-ray produce images to view amount & location of fat Hydrostatic (underwater) weighing Most accurate In this method a person is submerged and weighted under water; Percent body fat can be calculated from body density b/c muscle has a higher density than fat. This means that people with more fat tend to float and people with less fat (more muscle) tend to sink and weigh more under water Skinfold measurements Measures the thickness of fat under the skin. Measurements are taken at several sites and plugged into formulas that predict body fat percentages. Electrical Impedance Analysis Electrodes are attached to the body and an electrical current is transmitted from electrode to electrode. The electrical current favors the path of fat free tissues (prefers lean tissue). A computer calculates the fat percentages from measurements of current. Scanning procedures CT scan, MRI, Dual-energy X-ray are highly accurate means of assessing body composition but use expensive equipment.

Energy Balance Energy balance equation: Energy in = caloric intake from food Energy out = caloric expenditure Resting metabolism Digestion Physical activity When energy in = energy out Maintain weight When energy in > energy out positive energy balance (Gain weight over time) When energy in < energy out negative energy balance (Lose weight over time)

Body Fat distribution and Health Apples Men and postmenopausal women Store fat in abdominal area Increased risk of high blood pressure, diabetes, early-onset heart disease, stroke, cancer Pears Premenopausal women Store fat in hips, buttocks, thighs Assessed by measuring waist circumference > 40 inches for men and 35 inches for women is considered a risk

Problems Associated with Very Low Levels of Body Fat Low % body fat has been linked to problems with the Reproductive, Circulatory, & Immune systems Female Athlete Triad Abnormal eating patterns Amenorrhea Decreased bone density

Factors Contributing To Excess Body Fat Genetic Factors Genes influence body size, shape fat distribution 300 genes have been linked to obesity Physiological Factors Metabolism Low BMR = Basal Metabolic Rate (number of calories you'd burn if you stayed in bed all day) Hypothyroidism Hormones Leptin Genes influence body size, shape and body fat distribution 25 to 40% of an individual’s body fat determined by genes 300 genes have been linked to obesity Physiological Factors Metabolism Sum of all biochemical reactions RMR (largest component) = energy required to maintain vital body functions Hormones Leptin- a hormone produced by adipose (fat) tissue that is carried to the brain and tells the brain how big or small the body’s fat stores can be. With this information the brain can regulate how much fat you can store Fat Cells – The amount of fat the body can store depends on how many fat cells are in it. When all the body’s fat cells are filled with fat it will make more fat increasing the body’s ability to store fat. Overeating can cause the body to make more fat cells, increasing the body’s fat stores and whether or not the body gets rid of fat cells is still up for debate. Carbohydrate Craving – may cause overeating and can lead to obesity. Animal studies have suggested that consuming carbohydrates increases brain levels of serotonin, a neurotransmitter that induces calmness. People with low levels of serotonin may consume crave and consume carbohydrates in order to experirence the improved mood and calmness

Factors Contributing To Excess Body Fat Lifestyle Factors Eating Easy access to high calorie foods Eating out of proportion Physical Activity Reduced Psychosocial factors Emotions Coping strategies Eating Easy access to high calorie foods Eating out of proportion Physical Activity Reduced Psychosocial factors Emotions- eating is often a way to deal with loneliness, anger, shame, sadness, etc.; obesity levels go down as income goes up; more women than men are obese at lower income levels but the oppositeis true at higher income levels In some families, food is used as a symbol of love and caring and is an integral part of family gathering, so it is cultural too Coping strategies

Psychological Problems associated with weight Body Image Severe body image problems Body dysmorphic disorder (BDD)

Eating Disorders Anorexia Nervosa - Failure to eat enough food to maintain a reasonable body weight Characteristics Fear gaining weight, distorted self-image, compulsive behaviors and rituals, excessive exercise Health Risks of Anorexia Nervosa amenorrhea Intolerant of cold Low blood pressure and heart rate Depression and suicide Medical complications Disorders of the cardiovascular, gastrointestinal, endocrine, and skeletal systems

Eating Disorders Bulimia Nervosa - recurring episodes of binge eating followed by purging Characteristics: Rapid food consumption, followed by purging; afterwards feels ashamed, disgusted, physically and emotionally drained. Health Risks: Erodes tooth enamel Cardiac arrhythmia Esophageal tearing Rupture of the stomach Menstrual problems Increased depression

Eating Disorders Binge-Eating - Similar to Bulimia except no Purging behavior. Eating patterns - very rapid, eating until uncomfortably full. Often eat as a way of coping. Likely to be obese. High rates of depression and anxiety