BIOL 1215 Principles of Nutrition CH 10-11

Describe how the prevalence of obesity in the United States changed between 1988-1994 and 2017-2018: percentage of overweight and obese people.

-According to data collected from a national survey, more than 42% of American adults over the age of 20 were obese in 2017-2018 -the percent of adults who are obese increased by 85% between 1988-1994 and 2017-2018. People who are classified as being obese can be further categorized into a subgroup of individuals who are "extremely" or "severely" obese." In 2017-2018, over 9% of adult Americans were classified as being extremely obese. This percentage tripled since 1988-1994.

Describe the difference between subcutaneous fat and visceral fat.

-Subcutaneous (sub = under; cutaneous [qu-tay′-nee-us] = skin) tissue holds skin in place over underlying tissues such as muscles. Subcutaneous tissue also contains adipose cells. When subcutaneous tissue has more adipose cells than other kinds of cells, it is referred to as subcutaneous fat. Subcutaneous fat helps insulate the body against cold temperatures and protects muscles and bones from bumps and bruises. Subcutaneous fat is unevenly distributed. This layer of fat is thicker in certain regions of men's and women's bodies, especially in the abdominal area, thighs, and buttocks -In addition to subcutaneous fat, the body has visceral (viss′-eh-rol) fat. Visceral fat also contains adipose cells, but this type of body fat is in the omentum, a structure that is under the abdominal muscles and hangs over the intestines (Fig. 10.3). Although there are some racial differences, women generally have more subcutaneous fat than men, whereas men tend to have more visceral fat than women. Excessive amounts of visceral fat and/or subcutaneous abdominal fat result in what is commonly called a "beer belly" or the "middle-age spread."

Describe the various ways body fat is measured and the pros and cons of each method.

-Underwater weighing involves comparing a person's weight "on land" to his or her weight when completely submerged in a tank of water. Lean tissue is denser than water; fat tissue is not as dense as water. Thus, a person who has more body fat will weigh less when under water than a person who has more lean tissue. The underwater weighing method can be an accurate way of assessing body composition. However, the method is not a convenient, easy, inexpensive, or practical way to estimate body fat because it requires special testing facilities. -Dual-energy x-ray absorptiometry (DXA) involves the use of multiple low-energy x-rays to scan the entire body. The method provides a detailed "picture" of internal structures, including fat deposits. During the scanning process, the equipment emits a dose of radiation that is lower than that used for a chest x-ray. Although DXA is a highly accurate way to estimate body fat content, the equipment is very expensive and not widely available outside of clinical settings. -The air displacement method assesses the volume of a person's body, which can be used to calculate his or her body composition. After being weighed on a very precise scale, the subject sits in the chamber of a device called the BOD POD. This device measures the volume of air in the chamber with the person in it and compares the value with the volume of air that was in the chamber when it was unoccupied. The person's volume is the volume of air that was displaced after the subject entered the chamber. Air displacement measurements provide highly accurate estimates of body fat content, but the measuring device is expensive and not practical for most consumers to use. -Bioelectrical impedance is a quick way to estimate body fat content. This method is based on the principle that water and electrolytes conduct electricity. Body fat resists the flow of electricity because fat tissue contains less water and electrolytes than lean tissue. The bioelectrical impedance device sends a painless, low-energy electrical current via wires connected to electrodes placed on the subject's skin. Within a few minutes, the device converts information about the body's electrical resistance into an estimate of total body fat. The method can be accurate, as long as the subject's hydration status is normal. Dehydration results in an overestimation of total body fat. Consumers can purchase a bioelectrical impedance device that resembles a bathroom scale, but scientific data about the machine's accuracy is lacking. -A common technique for estimating total body fat involves taking skinfold thickness measurements at multiple body sites, such as over the triceps muscle of the arm. The width of a skinfold indicates the depth of the subcutaneous fat at that site. To perform the measurements, a trained person pinches a section of the subject's skin, gently pulls it away from underlying muscle tissue, and uses special calipers to measure the thickness of the fat. After taking the measurements, the values are incorporated into a mathematical formula that provides an estimate of the subject's amount of body fat. Skinfold thickness measurements are relatively easy and inexpensive to perform, but the method's accuracy largely depends on the skill of the person performing the measurements. Also, the technique may underestimate total body fat when used on overfat subjects. However, by combining data collected from skinfold, waist and hip circumference, and body frame (skeletal joint) measurements, researchers can obtain more reliable estimates of an individual's total body fat.

Describe medications and surgeries that are options for treating overweight and obesity: orlistat (Xenical, Alli) and gastric bypass.

-orlistat reduces fat digestion by about 30%. The undigested fat is eliminated in the feces and can cause an oily, unpleasant discharge. The fat carries fat-soluble vitamins along with it, and these micronutrients are eliminated in feces as well. Therefore, patients using orlistat often need to take a vitamin supplement that contains fat-soluble vitamins. Women who are pregnant or may become pregnant should consult their physicians before using these medications. Although prescription medication can aid weight-loss efforts, their use does not replace the need to reduce calorie intake and increase physical activity. -Bariatric (bar-ee-a′-tric) medicine is the medical specialty that focuses on the treatment of obesity. Bariatric surgery can be an effective method of treating people who are extremely obese (have BMIs greater than or equal to 40) or have BMIs of greater than or equal to 35 and serious health problems because of their obesity. Such surgical procedures drastically reduce the size of an obese person's stomach, markedly limiting his or her food intake. Patients who have bariatric surgery may lose significant amounts of their excess weight. Most patients, however, regain some weight within 10 years after the surgery.46 Aside from helping obese people lose considerable amounts of weight and maintain the loss, bariatric surgery can produce dramatic health benefits. Patients often achieve normal blood pressure, glucose levels, and triglyceride levels after surgery. Furthermore, overall death rates are lower for extremely obese people who lose weight after undergoing bariatric surgery. Such surgeries are relatively safe: Fewer than 1% of patients die as a result of a bariatric surgical procedure.

Explain the difference between overweight and obesity: BMI - body mass index.

-overweight refers to having extra body weight that is contributed by bone, muscle, body fat, and/or body water -Obesity is a condition characterized by excessive and unhealthy amounts of body fat. -To determine whether a person's weight is healthy, overweight, or obese, medical experts generally use the body mass index (BMI). BMI is a numerical value that reflects body weight adjusted for height

Describe practical steps that overfat people can take to reduce their body fat.

-planning menus -grocery shopping -food preparation -eating behavior -holidays and parties -restaurants -physical activity -self-monitoring -rewards for new behaviors -changing negative thought patterns

Explain the importance of optimal nutrition for athletes.

Dehydration and overhydration detract from optimal physical performance and can cause serious health problems. Regardless of how well an athlete eats, if this person lacks the physical traits that are necessary for success in his or her chosen sport, the athlete will find it difficult to compete effectively. Athletes must also be highly motivated to compete and engage in a well-designed intensive training program to maximize their physical capabilities. Nevertheless, optimizing an athlete's diet may provide a competitive advantage, especially for sporting events in which hundredths of a second can mean the difference between finishing first and finishing second. Athletes and coaches often believe misinformation concerning the value of dietary supplements, certain foods, and fad diets for optimizing physical health and performance. Such beliefs can lead to diet-related practices that are useless and a waste of money. In some cases, these practices are harmful or even deadly.

Explain the difference between having an eating disorder and practicing disordered eating.

Eating disorders are psychological disturbances that lead to abnormal physiological changes and dangerous health complications. An eating disorder is not the same as disordered eating. Disordered eating is chaotic and abnormal food-related practices, such as skipping meals, limiting food choices, following fad diets, and bingeing on food. Disordered eating behaviors are temporary, and they often occur when a person is under a lot of stress or wants to lose weight quickly. When a person adopts disordered eating behaviors as a lifestyle, the practices can become harmful and lead to serious eating disorders.

Describe the three major ways the body uses energy.

Energy output (energy expenditure) refers to the energy (calories) cells use to carry out their activities. For example, muscle cells need energy to contract, liver cells use energy to convert toxic compounds to safer substances, and intestinal cells need energy to absorb certain nutrients. The following sections discuss the major ways the body uses food energy.

Identify three sources of caffeine, and discuss the effects that the substance can have on the body.

Enhances fat metabolismDelays depletion of muscle glycogenIncreases alertness Consuming 3-6 mg of caffeine/kg of body weight about 1 hour before exercise can benefit certain athletes. High doses can cause nervousness, shakiness, and sleep disturbances; very high doses can be deadly. Intakes that cause the kidneys to eliminate more than 15 mcg of caffeine per ml of urine are banned by the National Collegiate Athletic Association. coffee red bull stay awake pills

Identify two ergogenic aids that have been banned by at least one athletic association and their effects on the body: caffeine, anabolic steroids.

It is important to note that certain dietary supplements are known to be unsafe, and the use of others is restricted or banned by major athletic organizations. For example, in 2004, the U.S. Food and Drug Administration (FDA) banned the use of ephedrine-containing supplements. Ephedrine (ephedra, ma huang) increases central nervous system activity, but the drug can cause serious, even deadly side effects. The following section discusses the ergogenic properties of caffeine. Athletes who have more than 15 micrograms of caffeine per milliliter (mcg/ml) of their urine can be banned Answers will vary but should include ephedra-containing supplements, caffeine (high intakes), anabolic steroids, and growth hormone.

Describe the health consequences of eating disorders and professional forms of treatment of eating disorders.

It may be difficult to talk with someone who you suspect has an eating disorder. If someone you know has an eating disorder, it is important to encourage the person to seek help as soon as possible to avoid serious health consequences. In academic environments, professional help is often available at student health centers and student guidance or counseling facilities on campus. A multidisciplinary group of experts in nutrition, mental health, and medicine is necessary for optimal treatment of eating disorders.69 Treatment should include psychotherapy while also addressing critical nutritional needs and other medical conditions. RDNs play a critical role in assessing and treating eating disorders, including providing nutritional counseling. RDNs can help stabilize healthy eating patterns and improve patients' nutrient status by providing appropriate medical nutrition therapy. Furthermore, experts in nutrition can play an important role in helping patients avoid relapse once recovery is underway. Treatment for eating disorders can occur in several settings. Inpatient hospitalization or residential care in a facility that specializes in the treatment of the disorders may be required when the patient's medical complications become life threatening. However, eating disorder treatment most often occurs in outpatient care settings. Outpatient care may involve individual, group, or family counseling. Treatment of eating disorders may also include prescription medications. Participation in eating disorder support groups may help prevent relapse. Cognitive behavioral therapy (CBT) is a major treatment approach for BN and BED.88 CBT is a general term used to describe psychological therapy approaches that address unhealthy emotions and behaviors. The therapy teaches people healthy coping strategies to use when under stress instead of fasting, bingeing, purging, or excessive exercise.

Describe serious health problems that are associated with having too much body fat and being obese in particular.

Overweight and Obesity Increase the Risk of: • Cardiovascular disease • Chronic low back pain • Hypertension • Loss of mobility • Type 2 diabetes • Fatty liver disease (not alcohol related) • Metabolic syndrome • Erectile dysfunction in men (impotence) • Polycystic ovary syndrome • Low-grade inflammation • Infertility • Gastroesophageal reflux disorder • Elevated blood lipid levels • Psychological depression • Gallstones • Certain cancers • Sleep apnea • Skin ulcers • Osteoarthritis

Identify the risk factors for eating disorders and disordered eating practices

• Being female • Being an adolescent (AN and BN) • Having a history of frequent dieting • Having a first-degree relative with an eating disorder • Placing a high degree of importance on having an "ideal" body shape • Being dissatisfied with one's body shape • Having a poor self-image and low self-esteem • Having a perfectionist personality • Being from a dysfunctional family • Being teased or bullied about one's weight • Being in an occupation or sport that emphasizes a lean body build

Identify characteristics of weight-reduction methods that are likely to be unsafe and unreliable.

A fad is a trendy practice that has widespread appeal among a population. After a period, however, people lose interest in the practice, and it becomes no longer fashionable. People often lose weight while following fad diets; however, they usually regain much of the weight that was lost while on the diet when they resume their prior eating and other lifestyle habits. Too often, people think of a weight-loss diet as a temporary change in their eating habits. Achieving a healthy body weight and maintaining that weight require making lifestyle changes that a person adopts for the rest of his or her life. However, many people who are overweight and obese seek quick fixes to lose weight, such as fad diets and dietary supplements promoted to "burn" or "melt" fat fast. Many overweight and obese people are attracted to dietary supplements for weight loss because they believe promoters' claims that their products are "magic bullets" for shedding unwanted weight quickly and effortlessly. Although several different types of weight-loss supplements are available, these products generally have not been scientifically tested in humans for safety and effectiveness.

Describe the measurement of heart rate and determination of target heart rate range.

A popular method of estimating the intensity of exercise is to use a percentage of your age-related maximum heart rate. To calculate your age-related maximum heart rate, subtract your age from 220. For example, a 27-year-old person would use 193 beats/minute (220 minus 27) for his or her age-related maximum heart rate. Your target heart rate zone is the range of heart rate that reflects the intensity of your exertion during physical activity. According to the Centers for Disease Control and Prevention (CDC) and American College of Sports Medicine (ACSM), for moderate-intensity physical activity, your target heart rate zone should be 64 to 76% of your age-related maximum heart rate.5 To determine your moderate-intensity "zone," take your age-related maximum heart rate and multiply this figure by 0.64 and 0.76.

Explain how to measure waist circumference and the usefulness of this information in regard to a person's health.

A quick and easy method to determine your risk of obesity-related disorders is to measure your waist circumference, which is an indicator of central-body obesity. Note the positioning of the tape at the top of the hip bones and not necessarily at the narrowest point. It is also important to use a measuring tape that does not stretch and to hold the tape around the waist, parallel to the floor. Central-body obesity is defined by a waist circumference of greater than 40 inches in men and greater than 35 inches in women

Describe features of reliable weight-loss plans or programs.

A safe and reliable weight-loss plan: Is safe and effective. Meets nutritional, psychological, and social needs. Incorporates a variety of common foods from all food groups. Fosters slow but steady weight loss. Does not require costly devices or diet books. Accommodates family and restaurant meals, parties and special occasions, ethnic foods, and food likes. Does not make the person feel deprived. Emphasizes readily available nutritious foods. Promotes changing habits that lead to overeating. Encourages regular physical activity. Provides suggestions for obtaining social support. Can be followed for a lifetime.

Describe how the set-point theory can explain why people often regain the weight they lose.

According to the set-point theory, the body's fat content (and, therefore, body weight) is genetically predetermined. The set point acts like a home thermostat, except that it regulates body weight instead of temperature. For example, a person infected with an intestinal virus tends to lose weight because he or she has no interest in eating for a few days. During and after recovery, the person generally regains the lost weight. This observation provides support for the set-point theory. Results of studies involving mice support the set-point theory.

Identify recommendations concerning the duration and intensity of physical activity to achieve good health: moderate-intensity vs. vigorous-intensity recommendations per week.

According to these guidelines, healthy adults under 65 years of age should perform: moderate-intensity physical activity for at least 150 minutes a week, or vigorous-intensity (high-intensity) physical activity for at least 75 minutes a week, and 8 to 10 strengthening exercises (8 to 12 repetitions of each exercise) that focus on major muscle groups at least twice a week

Identify factors that can influence the development of excess body fat.

Although an excess intake of calories in relation to calorie output causes weight gain, there is no simple cause of obesity. To lose weight, a person needs to create a negative energy state by eating fewer calories, expending more calories than the amount consumed, or taking both actions. For many people, however, it is not easy to alter calorie input and output. Numerous factors, including physiological, environmental, behavioral, and psychological forces, influence a person's calorie intake and expenditure.

Explain why some people are underweight.

An underweight individual has a BMI that is less than 18.5. Factors that contribute to underweight include genetics, lifestyle practices, serious chronic diseases, and psychological disturbances. It is often difficult to pinpoint a cause of underweight; multiple factors contribute to having a lower-than-average body weight. Individuals who inherit higher resting metabolic rates, tall body frames, or both may find it difficult to gain weight. Excessive physical activity can result in low body weight. Compared to sedentary adults, the bodies of rapidly growing, physically active children and adolescents have higher energy needs. If these children do not consume enough energy, they can lose weight. Chronic diseases such as cancer, tuberculosis, AIDS, and inflammatory bowel disease often result in severe weight loss that is difficult to treat. Some people who suffer from depression fail to eat enough food to support their energy needs, and they lose weight as a result.

List the major types of eating disorders and their signs: anorexia and bulimia.

Anorexia nervosa (AN) is a severe psychological disturbance characterized by self-imposed starvation that results in malnutrition and very low body weight (emaciation). A BMI of 18.5 is the lowest limit of what is generally considered a normal or healthy body weight for adults. • Severe constipation • Slow heart rate • Hypotension (low blood pressure) • Loss of normal menstrual cycles (women) • Low bone mineral density • Lanugo (delicate, dense, white hair on the skin) • Low thyroid hormone and decreased metabolic rate • Muscle wasting and weakness Bulimia nervosa (BN) is a severe psychological condition characterized by repeated episodes of binge eating followed by purging, such as self-induced vomiting, to prevent weight gain. Binge eating involves consuming an amount of food that is much larger than what a normal person would eat in a brief period of time, such as 2 hours. People with BN feel they have no control over their eating behavior during binge episodes. -Unlike people who have anorexia nervosa, individuals with bulimia nervosa are often difficult to identify by their appearance because they tend to have BMIs in the normal or overweight range (18.5 to less than 30). However, people with BN are often ashamed of their food-related behaviors and attempt to conceal their binge-purge practices from others. People with BN frequently induce vomiting by thrusting fingers deep into their mouths and, as a result, scrape their knuckles. Thus, characteristic signs of bulimia nervosa are bite marks and scars on the knuckles. Dentists often identify people who practice bulimic behaviors because the acid in vomit erodes the enamel on the surfaces of teeth, especially the backs of teeth. Eroded teeth develop many dental caries (cavities) and may become chipped and ragged in appearance. Persons with bulimia nervosa often have low self-esteem and feel guilty or depressed after a binge. Bingeing usually involves eating "forbidden" foods such as cakes, cookies, ice cream, and other high-fat, high-carbohydrate foods during binges. In cases of BN, different triggers may bring on a binge, including stressful situations, extensive dieting, and negative feelings about body weight, body shape, or food.

Describe the pros and cons of using amino acid supplements and other ergogenic aids for athletic performance.

Athletes often use ergogenic aids—foods, devices, dietary supplements, and even drugs ("doping")—to improve their physical performance. Bee pollen, dried adrenal glands from cattle, seaweed, freeze-dried liver flakes, and ginseng are among the dietary supplements that athletes consume as they hope to gain the competitive edge over their rivals. However, no reliable scientific evidence supports the effectiveness of most dietary supplements purported to have ergogenic effects.7 Nevertheless, many athletes firmly believe in the value of the performance-enhancing aids that they use. In many instances, the perceived benefits are more likely to result from the placebo effect than from actual physiological changes

Define basal metabolism: percentage of energy dedicated to basal metabolism.

Basal metabolism is the minimal number of calories the body uses for vital physiological activities after fasting and resting for 12 hours. To estimate the number of calories you need for your basal metabolism, first convert your weight in pounds to kilograms by dividing your weight by 2.2. (A kilogram is approximately 2.2 pounds.)

Describe factors that influence the basal metabolic rate.

Body composition Lean body mass is the major factor that influences the metabolic rate.11 Muscle tissue, a component of lean body mass, is more metabolically active than fat tissue. In general, a person who has more muscle mass will have a higher metabolic rate than someone with less muscle tissue. Sex Males generally have higher metabolic rates than women because they tend to have more lean body mass. Body surface area A tall, slender person who weighs 150 pounds has a higher metabolic rate than a shorter person who also weighs 150 pounds. Why? The body constantly loses energy in the form of heat that moves to the skin's surface and then into the environment. Because the taller person's body has more surface area than the shorter person's body, the taller individual has to generate more heat energy to replace that which is lost. Age Basal metabolism declines as one grows older, primarily due to the loss of fat-free tissues such as muscle. After 20 years of age, a woman's BMR declines about 2% and a man's BMR about 3% per decade.13 Therefore, the average adult needs about 150 fewer daily kilocalories per decade as he or she ages. As many adults grow older, they think their muscles have "turned into" fat. A muscle cell, however, cannot transform itself into a fat cell. During the aging process, lean tissue mass shrinks, as cells from muscle, bone, and organs die and are not replaced. Fat cells, however, can continue to develop throughout life, especially when a person overeats consistently. When adipose tissue expands in size, it can fill in spaces formerly occupied by muscle and organ tissues. Regular exercise helps build and preserve lean body mass, and to some extent, people can maintain a higher metabolic rate by being physically active as they grow older. Calorie intake Calorie intake also affects the metabolic rate. The body conserves energy use when calorie intakes are very low or lacking altogether. To enhance the rate of weight loss, a person who is overfat should reduce caloric intake while maintaining a normal metabolic rate. Because very-low-calorie diets reduce the metabolic rate, such diets are not generally recommended for weight loss. The factors that increase BMR: Increased muscle mass, Body temperature (Fever increases metabolism.), Excess thyroid hormone, Periods of growth (example, pregnancy), Greater body surface area (tall height), Lactation (milk production for breastfeeding), Exercise recovery, Stimulant drugs (example, caffeine), Emotional stress. The factors that decrease BMR: Decreased muscle mass, Starvation or very-low-calorie diets, Low thyroid hormone, Aging, Lower body surface area (short height).

Explain how cells make and use ATP: ATP, Mitochondria, Glucose.

Cells obtain energy by means of a complex series of chemical reactions that progressively break down (catabolize) macronutrients and alcohol to release the energy that is stored within them. Cells lose much of this energy as heat, but they capture some of the energy in high-energy compounds such as adenosine triphosphate (ATP). ATP forms when an inorganic phosphate group (Pi) bonds with adenosine diphosphate (ADP) and traps energy in the process glucose is the primary energy source for human cells. The simple sugar can be catabolized when free oxygen (O2) is unavailable (anaerobic) or available (aerobic). Catabolic processes involve oxidation, the removal of electrons from compounds to create new compounds. During glycolysis (glyco = carbohydrate [particularly sugar]; lysis = breakdown), the first stage of glucose oxidation, glucose is degraded to form two pyruvate molecules under anaerobic conditions (Fig. 11.5a). Glycolysis produces a small amount of ATP. If oxygen is available, each pyruvate molecule undergoes further oxidation in a stepwise series of chemical pathways called aerobic respiration. Pyruvate moves from the fluid within cells (cytoplasm) into mitochondria (Fig. 11.5b). Mitochondria are often referred to as "powerhouses" because much of the energy stored in glucose or other biological fuels is released within these cellular structures. In mitochondria, pyruvate molecules undergo complete degradation, and as a result, cells generate more ATP than during glycolysis. Oxygen is a key player in this phase of the process because the element bonds to hydrogen atoms that were released from pyruvate molecules, forming water (H2O) (see Figure 11.5b). When cells completely oxidize glucose to release energy, the end products are ATP, carbon dioxide (CO2), and H2O. Most of the CO2 is exhaled, and the H2O produced metabolically can help maintain proper body water volume. Besides glucose, triglycerides (fat), amino acids, and alcohol are also sources of ATP. Figure 11.6 summarizes the basic pathways that dietary protein, carbohydrate, and fat follow during energy metabolism

Compare "apple" to "pear" body shapes in terms of fat distribution and effects on health: central-body obesity.

Central-body obesity is characterized by a large amount of visceral fat ("spare tire") that spreads beyond buttocks and thighs. A person with central-body obesity is sometimes described as having an "apple" body shape. Men or women with central-body obesity have higher risks of serious chronic diseases, especially CVD and type 2 diabetes ("diabesity"), than people who have waists that do not extend beyond their hips. Women tend to store extra subcutaneous fat below the waist, primarily in the buttocks and thighs. Having this particular pattern of fat distribution (a "pear shape") adds stress to hip and knee joints that must carry the extra weight, but the pattern is not associated with increased risk of more serious chronic diseases such as type 2 diabetes.

Describe factors that influence hunger and satiety.

Hunger is an uncomfortable feeling that drives a person to consume food. Thus, hunger is the need to eat. Satiety is the sense that enough food or beverages have been consumed to satisfy hunger. An area of the hypothalamus, a structure in the brain, controls hunger and satiety. Scientists think this region functions as a "hunger/satiety center." The stomach, intestines, and fat tissue produce certain proteins, such as hormones and peptide YY, that stimulate nerve cells involved in the regulation of hunger and satiety.

Identify four key elements that are necessary for weight loss and weight maintenance.

Four key elements necessary for weight loss and maintenance are motivation, calorie reduction, regular physical activity, and behavior modification.

Describe the roles of hormones and peptides in regulating hunger: ghrelin and leptin.

Ghrelin (grel′-in), a hormone secreted mainly by the stomach, stimulates eating behavior. Some scientists think that reducing ghrelin production or activity is the key to helping people lose or maintain their weight. The small and large intestines release peptide YY, a protein that signals the stomach to reduce ghrelin secretion. The small intestine also releases cholecystokinin (CCK), the hormone that stimulates the gallbladder to contract and the pancreas to release digestive enzymes. Additionally, CCK stimulates the brain and other nervous tissue, suppressing appetite as a result. Fat cells secrete leptin, a hormone that reduces hunger and inhibits fat storage in the body. A person's blood leptin level is directly proportional to his or her amount of body fat.25 The brain obtains information about the status of body fat stores by monitoring the level of leptin in blood. When researchers administer leptin to genetically engineered mice that cannot synthesize the hormone, the rodents lose weight. Studies involving humans, however, generally find that obese people produce high amounts of leptin, but their bodies resist the hormone's hunger-suppressing action The illustration A shows ghrelin in the stomach stimulates hunger that signals the hypothalamus so that brain thinks of hunger. The illustration B shows leptin from adipose tissue, CCK from small intestine, peptide YY from small intestine and large intestine, inhibits hunger by signaling the brain and stomach for satiety.

Explain why it is important to have healthy amounts of body fat: healthy percentage of body fat. See Table 10.3 on page 389.

Healthy 13-21% (men) 23-31% (women) It is important to note that the average healthy young woman has more body fat than the average healthy young man because she needs the extra fat for hormonal and reproductive purposes. Adults tend to gain adipose tissue as they age, but for elderly persons, some additional fat does not necessarily contribute to serious health problems. The extra fat may provide some health benefits, such as providing an energy reserve for a very ill person who cannot eat. Furthermore, the extra padding of fat may protect a person from being injured by falling.

Classify a person's BMI as underweight, healthy, overweight, obese, or extremely obese.

Healthy BMIs range from 18.5 to 24.9. Overweight adults have BMIs that range from 25.0 to 29.9; obese adults have BMIs that range from 30.0 to 39.9. People whose BMIs are 40 or higher are classified as extremely obese

Describe heat-related illnesses, including prevention and treatment of these conditions: heat cramps, heat exhaustion, heat stroke, dehydration, water intoxication.

Heat Cramps Painful muscle cramps, usually in legs or abdomen Very heavy sweating Tiredness Thirst If heat cramps are not treated effectively, the person develops heat exhaustion. Heat Exhaustion Dark urine Cool, moist skin Weakness Light-headedness or dizziness Headache Nausea and vomiting To treat heat cramps or heat exhaustion, move the victim to a cool or shady place and have the person lie on his or her back with legs elevated 12 inches. To relieve leg cramps, massage the affected muscles until they relax. Cool the person by fanning, spraying with cool water, or giving a cool sponge bath. It is also very important to have the victim drink cool water or a sports drink, unless the person is vomiting or has lost consciousness. People with heat exhaustion should be monitored closely because the condition can rapidly develop into heatstroke. Heatstroke Dry, hot, red skin High fever (over 104°F) Rapid, shallow breathing Confusion, irrational behavior Seizures, loss of consciousness Heatstroke is a medical emergency that needs to be treated by trained medical staff. If you suspect that a person has heatstroke, summon emergency medical assistance immediately (dial 911) and move the victim to a cool environment. While waiting for professional medical care to arrive, give the patient cool water to drink (if he or she is conscious and not vomiting) and spray the person's skin with cool water. Even a small degree of dehydration can lead to declines in an athlete's endurance, strength, and overall performance. Moreover, body temperature rises when dehydration occurs, increasing the risk of heat-related illness. Athletes following these drinking plans must be monitored to ensure fluids are not overconsumed, leading to water intoxication (hyponatremia). Nevertheless, athletes should avoid losing more than 2% of their body weight during exercise. To avoid water intoxication, athletes should drink water according to their thirst or follow a closely monitored fluid consumption plan. If an athlete gains weight while exercising, he or she may be retaining too much fluid.

Identify the key components of a good aerobic workout regimen.

Ideally, you should establish a regular time for exercising that fits into your daily routine. To be effective, your aerobic workout program needs to include the following components: Warm-up Warming up muscles can increase your joints' range of motion (flexibility) and may decrease your risk of injury. Stretching for 5 to 10 minutes is a good way to warm up. Start with smaller muscle groups such as the arms and progressively work toward stretching larger muscle groups in the legs and abdomen. Hold your position in the stretch for 15 seconds and do not bounce. If stretching causes pain, stop immediately. "No pain, no gain" is not true: Pain is an indication of injury. Another way to warm up is to perform 5 to 10 minutes of the anticipated activity but at a low intensity. For example, if you walk for fitness, warm up by walking at a slower pace. Aerobic workout To obtain substantial health benefits, you should engage in some form of aerobic activity regularly. A comprehensive aerobic workout emphasizes the type, duration, frequency, intensity, and progression of exercise. Type: The kinds of exercise you choose should increase your heart and breathing rates and involve rhythmic movements of large muscle groups in the legs. Examples include brisk walking, running, swimming, and cycling. If you swim, add some weight-bearing activities, such as walking, to your comprehensive fitness plan. Weight-bearing exercises place stress on your bones, increasing their strength. Duration: Duration is the amount of time spent in an exercise session. A session should generally last at least 20 to 30 minutes, depending on intensity, not including time spent warming up and cooling down. Ideally, the exercise session should be continuous (without stopping), but multiple 10-minute bouts of moderate to intense activity with rest periods in between are also acceptable. Frequency: The frequency of exercise describes the number of times that the activity is performed, generally on a weekly basis. To derive significant health benefits, the frequency of aerobic exercise should be at least five times per week. By exercising daily, you can enjoy even greater benefits. Intensity: Health benefits can occur when you achieve at least a moderate level of intensity during exercise. Progression: Progression, the final component of a comprehensive fitness plan, refers to the gradual increase in the frequency, intensity, and duration of exercise that occurs over a period. Page 463 Cool-down: To cool down, you can repeat the same stretches you performed during warming up. Stretch for 5 to 10 minutes. Cooling down may prevent injury and reduce muscle soreness.

Compare states of positive and negative energy balance.

If your calorie intake is lower than your calorie output, you are in negative energy balance. In this state, your body needs more calories to carry out its activities than your diet is supplying. Therefore, your body metabolizes stored fat for energy. Weight loss results from being in a negative energy state. Over time, you will notice your clothes have become baggy as your adipose tissue shrinks. If your calorie intake from macronutrients (and alcohol) is greater than your calorie output, you are in a state of positive energy balance. In this state, your body stores excess dietary fat in adipose cells. Additionally, the body converts surplus dietary carbohydrate, protein, and alcohol to fat and stores that fat in adipose cells. Weight gain results from being in a positive energy state, and eventually, you will notice that your clothes seem to have shrunk.

Explain the pros and cons of bariatric surgical procedures: gastric bypass.

In the United States, two common surgical approaches to treating obesity are the Roux-en-Y (ru-en-wi′ ) gastric bypass and gastric banding procedures. Both of these operations can be performed laparoscopically, that is, by using several small incisions that allow surgeons to insert instruments and a video camera into the abdomen. Laparoscopic bariatric surgical procedures reduce recovery time and the risk of infections. During the Roux-en-Y gastric bypass operation, the surgeon staples across the upper part of the stomach to create a small pouch. This procedure reduces the obese patient's stomach capacity to about 1.5 oz, which is approximately the volume of one egg. (Normally, the stomach's capacity is about 32 oz.) Additionally, the surgeon cuts the small intestine and attaches the lower end of it to the newly formed stomach pouch. The "bypassed" section of the intestine does not receive food, so digestion and absorption are reduced as a result of the surgery. Complications often associated with gastric bypass surgery include intestinal blockage and bleeding, leaks along the staple site, blood clot formation, and wound infections. After surgery, gastric bypass patients can develop micronutrient deficiencies and some bone loss. However, patients can reduce their risk of nutrient deficiencies by taking vitamin and mineral supplements.

Describe ways to gain weight safely and sensibly.

Many underweight individuals want to gain weight, especially muscle mass. For an underweight person, gaining weight can be just as challenging as losing weight is for a person who is overfat. To gain weight, adults who are underweight can gradually increase their consumption of calorie-dense foods, especially those high in healthy fats. Fatty fish, such as salmon; olives; avocados; seeds; low-fat cheeses; nuts and nut butters; and granola made with dried fruit, seeds, and nuts are high-calorie nutritious food choices with low saturated-fat content. Additionally, people who are underweight can replace beverages such as soft drinks with more nutritious calorie sources, such as 100% fruit juices, smoothies, and milk shakes made with peanut butter and reduced-fat ice cream. Following a regular meal and snack schedule also aids in weight gain and maintenance.

Describe how each energy system supplies ATP for muscles and under what conditions a particular energy system functions: PCr-ATP energy system (anaerobic, phosphocreatine, brief intense--few seconds--activity of muscles); Lactic Acid Energy System (anaerobic, muscles produce lactic acid, brief--30 to 40 seconds--activity of muscles); Oxygen Energy System (aerobic, muscles and every other body cell).

PCr. Muscle cells break down PCr into creatine (Cr) and inorganic phosphate Pi, releasing energy to form ATP from ADP and Pi (a). When the intense activity stops and there is no need to maintain high levels of ATP, an inorganic phosphate group bonds with creatine to recycle PCr (b). The illustration shows a cell inside which glucose is converted to two pyruvate molecules while releasing an ATP. The two pyruvate are converted to 2 lactic acid which is then converted to lactate. In anaerobic conditions, muscle cells rapidly metabolize glucose to lactic acid and then to lactate. This process produces a small amount of ATP. Lactate enters the bloodstream. The liver can remove lactate from blood, convert it into glucose, and release the simple sugar into the bloodstream, if the fuel is needed. If the body does not need the energy, the liver converts glucose to glycogen. You would not be able to enjoy activities such as walking at a fast pace, swimming laps, playing a game of soccer or basketball, or other continuous types of physical activity if your muscles depended only on the anaerobic energy systems. When muscle cells have plenty of oxygen, such as during low- to moderate-intensity exercise, they can metabolize glucose completely to CO2 and H2O. In fact, the availability of oxygen enables cells to produce about 18 times more ATP-energy than the amount produced by anaerobic systems. The oxygen (aerobic) energy system enables muscles to continue working during intense physical activities that last for 2 minutes or longer.7 The ability to obtain energy aerobically is useful for endurance athletes because it allows their muscle cells to contract repeatedly for hours.

Define physical fitness.

Physical fitness may be defined as the ability to perform moderate- to vigorous-intensity activities for a reasonable amount of time, without becoming excessively fatigued.

Describe the health benefits of performing exercise on a regular basis: See Figure 11.1 on page 439.

The benefits of being physically active: Reduces stress and improves self-image; Promotes psychological well-being; May protect the brain from changes associated with the aging process; Increases muscle mass and strength; Reduces risk of colon cancer (cancer of the large intestine); Increases flexibility and Balance, Strengthens bones and improves the function of joints; Reduces feelings of depression and anxiety, Reduces the likelihood of sleep disorders Increases cardiovascular function and improves blood lipid profile, Reduces blood pressure, Reduces risk of breast cancer, Aids in weight loss/weight control, Improves blood glucose regulation; reduces risk of type 2 diabetes. Entire body: Improves immune function and Reduces the risk of dying prematurely.

Identify high-carbohydrate/low-fat foods: for meals and snacks, glycogen loading.

Table 11.3 provides some menu ideas for high-carbohydrate, low-fat pre-event meals that supply approximately 200 g of carbohydrate. Eating fatty foods such as sausage, bacon, sauces, and gravies is not recommended because they may contribute to intestinal discomfort while competing Meal A -Instant oatmeal, cinnamon-flavored, 2 packetsFat-free milk, 8 oz -Canned peaches, light syrup, sliced, 1 cup -Orange juice, 8 ozRaisin bread, toasted 2 slicesSoft margarineJelly, 2 Tbsp Meal B -Pasta salad, 1½ cupsFrench bread, 4 ozSoft margarine, 1 Tbsp -Apple juice, 8 oz -Frozen yogurt, 1 cup Meal C -Cornflakes, ready-to-eat cereal, 1½ cupFat-free milk, 8 ozBanana, medium -Orange juice, 8 oz -English muffin, toastedSoft margarine, 1 TbspJelly, 2 TbspNutty energy bar* High-carbohydrate, low-fat food choices for pre-event meals or snacks include cereal with fat-free milk, bagels, dried fruit, pretzels and a sports drink, cooked oatmeal with fruit, pasta, baked potato topped with yogurt, and toasted bread with jelly

Explain how a person can improve his or her aerobic capacity.

The ability of your heart and lungs (sometimes referred to as the cardiorespiratory system) to deliver oxygen to muscles determines your capacity for intense aerobic physical activity. Scientists can use special equipment to estimate maximal oxygen intake (aerobic capacity or VO2max) during vigorous physical exertion. A simple way to determine if you are nearing your aerobic capacity is to engage in vigorous exercise and note when your breathing rate increases to the point that you cannot carry on a conversation. You can increase your aerobic exercise capacity by engaging in an endurance training program that gradually increases the intensity level of activities. Such training improves your muscle cells' ability to generate ATP rapidly. However, even highly trained athletes experience muscle fatigue after increasing the time they usually spend performing intense muscular exertion.

Explain what is meant by having "thrifty genes."

Thrifty genes could benefit people during periods of food deprivation, such as famine. During times when food was plentiful, individuals who had thrifty metabolisms stored more of the excess energy from food as body fat than persons who did not have such efficient metabolisms. The people who lacked thrifty metabolisms wasted the excess food energy as body heat. As a result, the energy-"thrifty" people were more likely to survive periods of starvation than the other persons. In many modern societies, however, high-calorie food is available 24 hours a day and starvation is unlikely. As a result, having thrifty metabolisms is no longer beneficial because depositing excess body fat often results in serious health problems. If you gain weight easily, you may have inherited a thrifty metabolism

Describe the physical activity pyramid and explain how it can be used as a guide for developing a personal exercise plan: See Figure 11.3 on page 440.

The base of the physical activity pyramid has: activities of daily living (most days of the wee, accumulate 30 plus minutes): Gardening, raking leaves, mowing the lawn, walking the dog, cleaning the house, playing with your children. The second step of the pyramid has: Aerobic Exercise (3 to 5 days per week, for at least 150 minutes): Running, cycling, in-line skating, stair stepping; Flexibility Exercise (No specific recommendations for frequency and duration): Stretching of major muscle groups. Lunges, toe touches, shoulder rolls; Strength Exercise (2 or more days/week, 8 to 10 exercises 1 set of 8 to 12 reps): Bicep curls, tricep presses, squats, lunges, push-ups. The third step of the pyramid: Light Recreational Activity (2 to 3 days per week) Bowling, walking (fast pace), line dancing, doing yoga. The tip of the pyramid has: Sedentary Activity (occasionally): Sitting, driving, watching TV, using a computer, texting, talking on the phone.

Explain the difference between physical activity and exercise.

The human body is designed for physical activity, movement that results from skeletal muscle contraction. Exercise refers to physical activities that are usually planned and structured for a particular purpose, such as having fun or increasing muscle mass.

Identify the macronutrients used as energy sources and under what conditions: carbohydrates (glucose, glycogen) vs. lipids (fats) vs. proteins (amino acids).

The intensity of a physical activity largely influences the relative amounts of fatty acids and glucose that muscles metabolize for energy. Glucose supplies only about 40% of the energy needed to sustain a person who is resting or engaged in very light to light activities, such as watching TV, typing, and walking. Fat is the primary fuel muscles use while resting or engaged in low- to moderate-intensity physical activities.9 During high-intensity exercise, the rate of fat oxidation decreases while that of glucose oxidation increases. An individual's level of training influences the ratio of glucose to fatty acids that his or her muscles use during exercise. Trained endurance athletes tend to oxidize more fat when exercising at the same intensity than untrained persons.10 As a result, muscle cells of trained athletes "spare" glycogen; that is, they conserve their supply of glucose. By sparing their glycogen supplies, athletes can enhance their capacity to exercise longer. ATP At all times All types Phosphocreatine (PCr) All exercise initially; short bursts of exercise thereafter Shot put, high jump, bench press Carbohydrate Anaerobic High-intensity exercise, especially lasting 10-180 seconds100-meter dash (sprint) Aerobic Exercise lasting 2 minutes-3 hours or more; the higher the intensity of exercise, the greater the useBasketball, swimming, jogging Fat At rest Sitting Exercise lasting more than a few minutes; low- to moderate-intensity physical activities30-minute brisk walk Protein Low amounts during all exercise, slightly more during endurance exercise, especially when carbohydrate fuel is lacking Long-distance running

Explain the concept of energy balance.

Your body is in a state of energy equilibrium and "balanced" when your calorie intake from food and beverages equals your calorie output for basal metabolism, physical activity, and TEF By maintaining a balanced energy state, your weight will remain relatively stable over time.

Estimate an athlete's energy, protein, and other nutrient needs: dietary fat, carbohydrate, and protein recommended ranges.

athletes may require 3000 kcal/day or more to support their energy needs and maintain their weight Table 11.2 presents a sample daily menu that is nutritionally adequate, supplies approximately 5000 kcal/day, and provides ample amounts of carbohydrate. The Adequate Intake (AI) for total water intake is approximately 11 cups (2.7 L) and 15.5 cups (3.7 L) for young women and men, respectively. Athletes generally require more water than nonathletes to keep their bodies cool during muscular activity. For most physically active people, fat should supply 20 to 35% of energy, which is the Acceptable Macronutrient Distribution Range (AMDR) for fat that is recommended for the general population To calculate your recommended range of carbohydrate intake for endurance activities, multiply your weight in kilograms by 6 and then by 10. The adult RDA for protein is 0.8 g/kg of body weight.15 During prolonged physical activity, muscles lose some protein because they metabolize certain amino acids for energy. Furthermore, extra amino acids are needed to repair and increase muscle tissue after exercise (recovery).13 According to a recent review, athletes who engage in moderate-intensity exercise generally need 1.4 to 2.0 g of protein/kg of body weight/day.12 Athletes who perform vigorous intensity or resistance exercise may benefit from consuming more than 2.0 g/kg of body weight daily.