NSC 170C1 1st Edition Lecture 21 Outline of Last Lecture I. A Healthy Weight: What Is It, and How Do You Maintain It?Outline of Current Lecture I. What is overweight? II. FactorsIII. How to keep a healthy weightA. Maintaining Current LectureI. What is overweight and why is it a problem?A. In the early 1960s, fewer than 32 percent of Americans were overweightB. Today, over 65 percent of Americans are overweight; 33 percent are obesei. In 2005, obesity was the most frequently covered health story in the mediaii. Americans spend over $45 billion annually on weight-loss solutionsiii. Medical complications associated with overweight cost the U.S. health care system $92 billionC. Overweight (BMI 25 to 29.9) means that a person is as little as 10 to 15 pounds more than a healthy weightD. Obesity (BMI ≥30) means a person carries 25 to 40 or more pounds of excess weightE. Being overweight can increase risk of i. Hypertension, stoke, and heart diseaseii. Gallbladder diseaseiii. Type 2 diabetesiv. Certain cancersv. Osteoarthritisvi. Sleep apnea II. Factors that contribute to overweightA. Hunger and Appetite Affect What and When You Eati. There is a difference between the physiological need for food (hunger) and the psychological factors that prompt you to eat (your appetite)ii. Hunger is the physical need for nourishment that drives you to consume food.iii. Satiety is the sensation that you have had enough to eat. It determines the length of time between eating episodesa) Anything that increases satiety will help decrease weight gain and vice versa.B. Physiological Mechanisms Help Regulate Hunger and Satietyi. Feedback mechanisms involving the mouth, stomach, intestines, and brain work together to increase or decrease your hungera) The hormone Ghrelin, produced by the stomach during fasting or between meals, stimulates hungerb) The hormone Leptin, produced by adipose tissue, suppresses hungerand food intakeii. When food enters your mouth, sensory signals are sent to the brain that tell you whether to continue eatingiii. Distention of the stomach (depending on the size of the meal) signals the brain to decrease hungera) Also causes release of cholecystokinin, a hormone that decreases hunger and helps you feel satisfiediv. Once food reaches the small intestine, the protein, fatty acids, and monosaccharaides stimulate feedback to the brain to decrease hungera) Nutrient absorption leads to insulin release, which also causes the brain to decrease hungerC. Genetics play a role in determining body weight i. Differences in the level or functioning of some hormones can influence bodyweight and appetitea) Genetically high levels of ghrelin may cause some people to overeat and become obeseii. Individuals genetically prone to being Leptin deficient become massively obeseiii. May affect how calories are expended by influencing thermogenesis, theproduction of heat in body cellsiv. May cause different rates of nonexercise-associated thermogenesisv. Genetic “set point” may determine body weighta) Theory that the body fights to remain at a specific body weight with mechanisms that oppose significant weight loss or gainD. Genetics Interacts with your environment to influence your weighti. Individuals with a genetic propensity to become overweight experience greater challenges to prevent obesity in an environment conducive to weight gainii. Gene-environment interactiona) Example: High rate of obesity among Pima Indians living in Arizona versus those living in MexicoE. Environmental Factors Can Increase Appetite and Decrease Physical Activityi. Environmental stimuli can drive your appetitea) Aromas, events, people, and the convenience of obtaining food can encourage eating even when you’re not hungryiii. Environmental issues are feeding Americans’ energy imbalancea) We work more and cook less1. Almost one-third of Americans’ daily calories come from ready-to-eat foods that are prepared outside the home2. Between 1972 and 1995, the prevalence of eating out increased by almost 90 percent3. Dining out frequently is associated with a higher BMIb) We eat more (and more)1. We have greater access to a wider variety of foods2. The portion sizes of many foods have doubled or tripled over the past 20 years3. People tend to eat more when larger portions are served4. Larger food packaging and serving dishes are also influencing Americans to eat morec) We sit more and move less.1. We expend less energy both at work and during leisure time2. Technology allows us to communicate with coworkers and clients without leaving our desk3. Labor-saving devices such as riding lawnmowers anddishwashers can reduce daily energy expenditure byas much as 100 calories a day4. More than half of Americans fall short of physical activity recommendations5. Our leisure and social activities have become more sedentary6. Over 40 percent of American homes have three or more TVs7. 2- to 18-year-olds log more than 5 hours of “screen time” dailyIII. How Can You Lose Weight Healthfully?A. An energy deficit of 3,500 calories is required to lose a pound of fati. A deficit of 250 to 500 calories daily will result in weight loss of ½ to 1 pound weeklyB. Health experts agree that a person needs to adjust three areas of life for successful, long-term weight lossi. Dietii. Physical activityiii. Behavior changeC. Three Pieces of the Long-Term Weight-Loss PuzzleD. Eat Smart Because Calories Counti. Taking in fewer calories and burning off more will result in weight loss.a) However, cutting back too drastically often results ina failed weight-loss attemptii. A key strategy is to eat a healthy, balanced diet that is not only lower in calories but also satisfyingiii. One way to add heft and satiation to lower-calorie meals is by including higher-volume foodsE. Eat More Vegetables, Fruit, and Fiberi. High-volume, low-energy-density foods fill you up before they fill you outa) Fruits and vegetables have a high water content, which givesthem bulkb) Whole grains contain filling fiberc) Low in fat and high in carbohydratesii. Research shows these foods are associated with increased satiety and reduced calorie intake and feelings of hungeriii. Overweight individuals consume less dietary fiber and fruits than normal-weight peopleF. Include Some Protein and Fat in Your Mealsi. Protein has a dramatic effect on satietyii. Fat also prolongs satiety by slowing the movement of food out of the stomach into the intestinesa) Including some lean protein and