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Transcript
Chapter 17 Nutrition Purpose • To provide the fitness professional with a fundamental overview of proper nutrition and how it influences body composition alteration, performance enhancement, and overall health. Objectives – Describe the macronutrients and their functions – Describe how the macronutrient composition of an individual’s food intake can affect satiety, compliance, daily energy expenditure, and weight control. – Provide basic nutritional recommendations for optimizing health – Dispel myths Nutrition • Definition – The sum of the processes by which an animal or plant takes in and uses food substances • Benefits of Proper Nutrition – – – – – Hasten the results of exercise Improve health and athletic performance Decrease risk of disease and illness Increase energy levels Alter body composition Standards of Practice – Personal trainers should be familiar with the concepts of nutrition. Integrating nutritional strategies with exercise will help clients achieve their desired outcomes. – The professional, legally qualified to practice in the field of nutrition, is a Registered Dietician (RD). – The RD is a specialized food and nutrition expert with extensive training who meets specified criteria Energy and Body Composition – By 2015, public health experts expect that 75% of all US adults will be either overweight or obese – The facts about weight loss and gain are quite simple. Eat fewer calories than are expended and there will be a reduction in weight. Conversely, consume more calories than are expended and there will be an increase in weight Daily Energy Needs – calorie (lower case c) is a unit of energy and is defined as the amount of heat energy required to raise the temperature of 1 gram of water 1 degree Celsius. – A Calorie (upper case C) or kilocalorie (kcal) is equal to 1,000 calories – Estimated total energy expenditure (TEE), also referred to as total daily energy expenditure (TDEE), is defined as the amount of energy (calories) spent, on average, in a typical day. Daily Energy Needs – TEE is actually the sum total of three different energy components: – Resting metabolic rate (RMR): The amount of energy expended while at rest; regulation. RMR typically accounts for 70% of TEE. – Thermic effect of food (TEF): The amount of energy result of the processing of food accounts for approximately 6–10% of TEE. – Energy expended during physical activity: Associated with physical activity accounts for approximately 20% of TEE. Macronutrients • • • • Protein Carbohydrate Lipids (Fat) Water Protein • Function – Build and repair body tissues and structures – Synthesize hormones, enzymes, and regulatory peptides – Can be used for energy with a lowcarbohydrate diet • Provides 4 calories per gram Protein • Structure – Made up of amino acids linked together by peptide bonds – Body uses approximately 20 amino acids to build different proteins Protein • Classification of Amino Acids – Essential • Cannot be manufactured in the body (or are manufactured in insufficient amounts) • Must be obtained through food or supplementation – Nonessential • Manufactured naturally in the body Protein in Foods • Complete Proteins – Food that supplies all essential amino acids in appropriate ratios • Meat, poultry, fish, dairy • Incomplete Proteins – Food source low or lacking in one or more essential amino acids • Vegetables, fruit, grains, legumes Factors Affecting Protein Requirements • Exercise – Increases oxidation of amino acids – Increases rate of protein turnover in lean body mass during recovery • Caloric Intake – Carbohydrates are often referred to as “protein sparing” because in adequate amounts, protein will not be used as energy – As total energy intake decreases, protein requirements increase Protein Intake Requirements • 10–35% of total caloric intake is generally recommended High-Protein Diets • More than 35% of total caloric intake from protein • Reported Side Effects – Increased urea production – Possible dehydration – Higher intake of saturated fat – Decreased glycogen stores Carbohydrates • Chief source of energy for all body functions and muscular exertion – Provide 4 calories per gram – Compounds containing carbon, hydrogen, and oxygen • For most moderately active adults, a carbohydrate intake of 45–65% is recommended • Classifications – Simple carbohydrates • Sugar, honey, fruit – Complex carbohydrates • Starch, whole grains – Fiber Digestion, Absorption, and Utilization • Simple Carbohydrates – Easily digested • Complex Carbohydrates – Require prolonged enzymatic activity to be broken down to simple-sugar form Fiber and Health • Higher intakes of dietary fiber are associated with lower incidence of heart disease and certain types of cancer • Recommended daily intake of dietary fiber is 25-35 grams • Provides bulk to the diet • Regulates the body’s absorption of glucose Carbohydrates and Performance • Anaerobic Activity – High-intensity, short-duration – Dependent on availability of glycogen • Aerobic Activity – Low-intensity, long-duration – Glycogen provides 50% of energy needs • Endurance Exercise – Carbohydrate-rich diet builds glycogen stores and aids in performance and recovery – A diet containing approximately 60% of caloric intake from carbohydrate is recommended – Complex carbohydrates should make up the majority of calories owing to their nutrient-dense nature Carbohydrate Recommendations • Before Exercise – Consume a high-carbohydrate meal (1–4.5 g/kg of carbs) 2 to 3 hours before activities lasting 60 minutes or more. • Liquid meal-replacement formula an option – Smaller meals or liquid snacks should be consumed closer to the exercise session. • Prevent gastrointestinal distress • Ensure glycogen refueling Carbohydrate Recommendations • Carbohydrate Loading – Endurance events lasting 90 minutes or more deplete muscle glycogen stores. – Carbohydrate-loading is used to increase muscle glycogen stores before competition. Glycogen-Loading Schedule Carbohydrate Recommendations • During Exercise – For exercise lasting longer than 60 minutes – Can help supply glucose to working muscles where glycogen stores may be depleting – Consume 20–40 oz. of a sports drink containing between 4 and 8% carbohydrate each hour (30–60 g carbs/hour) – Proper carbohydrate balance contributes to enhanced performance for the endurance athlete Carbohydrate Recommendations • After Exercise – Repeated days of strenuous activity decrease an athlete’s muscle glycogen stores – Within 30 minutes after exercise, consume 1.5 g/kg body weight of carbohydrate – Additional meals of 1.5 g/kg body weight every 2 hours are recommended to completely restore muscle glycogen Carbohydrate Recommendations • Altering Body Composition – Should make up the highest percentage of macronutrient calories during fat loss or muscle gain – The satiating value of complex carbohydrates is especially important when one is in a caloric deficit (for the goal of fat loss) – Very little data correlates carbohydrate intakes to increases in obesity Lipids • Sterols • Triglycerides • Phospholipids Sterols (Cholesterol) • • Naturally produced in the body (liver) and available in foods. Lipoproteins (fat-protein combination) are the cholesterol transporters in the body. – VLDLs (very-low-density lipoproteins) carry 5–15% of cholesterol in body tissues. – LDLs (low-density lipoproteins) contain the highest percentage of cholesterol in most people. – HDLs (high-density lipoproteins) – Low dietary fat intake, regular exercise, and body-weight regulation raise HDL levels. • Ratio of LDL:HDL is the current blood test used to evaluate the risk of cardiovascular disease. Triglycerides • Three fatty acids attached to a glycerol backbone Lipids • When triglycerides are metabolized, glycerol can be converted to glucose and provide energy. – Saturated fatty acids • • • • • • Hard at room temperature Commonly found in animal meats Lard Butter Coconut oil Palm oil Lipids • Unsaturated Fatty Acids – Implicated in increased HDL (“good” cholesterol) – Unstable (soft) at room temperature • Monounsaturated – Olive oil – Canola oil – Almond oil • Polyunsaturated – – – – Peanuts Macadamia nuts Safflower oil Corn oil Lipids • Functions – Provides energy – 9 calories per gram – Transports fat-soluble vitamins (A, D, E, K) – Cellular membrane structure and function – Precursors to hormones (testosterone) – Organ protection – Prolongs digestive process by slowing gastric emptying Lipid Recommendations • Fat Loss and Overall Health Goals – 20–35% of total calories from fat • 20-25% for athletes Digestion, Satiety, and Usage – Digestion of dietary fat starts in the mouth, moves to the stomach, and is completed in the small intestine. – Dietary fats stimulate the release of CCK, a hormone that signals satiety. Additionally, fats slow the digestion of foods assisting in blood sugar stabilization – Medium Chain Triglycerides (MCT’s) can be used for fuel Insulin Resistance and Obesity – The growing fat cell itself becomes insulin resistant, and the resulting prevalence of FFA will cause the body to favor the use of fat for energy at the expense of glucose. This becomes a vicious cycle, with the overweight condition leading to IR, which in turn leads to impaired glucose use. – High-fat diets are strongly associated with obesity, and thus insulin resistance and diabetes Water • General Recommendations – 3.0 L (13 cups) per day for men – 2.2 L (9 cups) for women – A fat-loss program requires an additional 8 oz. of water for every 25 pounds a person carries above ideal weight – Intake should be increased if client is exercising briskly or in a hot climate Importance of Water • Constitutes approximately 60% of the adult human body weight. • A fluid loss of 2% of body weight adversely affects circulatory function and decreases performance. • Benefits – – – – – – Improves endocrine gland function Increases the percentage of fat used for energy purposes Decreases appetite Distributes nutrients throughout the body efficiently Regulates body temperature Maintains blood volume Water and Performance • Effects of Dehydration – Decreased blood volume – Decreased performance – Decreased blood pressure – Decreased sweat rate – Decreased blood flow to skin – Decreased cardiac output – Increased heart rate – Increased perceived exertion – Increased use of muscle glycogen Guidelines for Fluid Replacement • Consume 14-22 oz. of fluid 2 hours before exercise. • Drink 6–12 oz. of fluid for every 15-20 minutes of exercise. • Fluids should be cool because of rapid gastric emptying. Guidelines for Fluid Replacement • If exercise is less than 60 minutes, water is the best choice for fluid replacement. • Ingest 16-24 oz. of fluid for every pound of body weight lost after exercise, especially if rapid rehydration is necessary. Altering Body Composition • Fat Loss – Makes small decreases in food and beverage calories and increase physical activity – Distribute protein, carbohydrate, and fat throughout the day and at each meal – Choose whole grains and fresh vegetables over refined grains and simple sugars – Avoid empty calories and highly processed foods – Drink 9–13 cups of water per day – Weigh and measure foods for at least 1 week Altering Body Composition • Lean Body Mass Gain – 4–6 meals per day – Spread protein intake throughout the day – Consume meal or drink of protein and carbohydrate within 90 minutes after exercise – Remember the importance of carbohydrate and fat in a balanced diet Do carbohydrates make me fat? • No – CHO are necessary nutrients – Select CHO high in fiber to help with satiety, blood sugar regulations and energy balance – Avoid overconsumption of processed CHO Does eating at night make me fat? • No – Weight gain is a result of eating too many calories, not the time of day you consume those calories Which is superior for weight loss, low-fat or low carb? • Neither – Weight loss is achieved when calories consumed are less than calories expended. Can I eat whatever I want as long as I exercise? • No – Weight gain is a result of eating too many calories – This is possible even if you exercise What are the risks of starvation diets? • • • • • Increased malnutrition Poor energy A behavioral pendulum Fatigue, constipation, nausea or diarrhea Gallstone formation Is consuming a high protein diet superior for muscle gain? • Active individuals need more protein than sedentary people. • 0.5-0.8 grams per pound (1.2-1.7 g per kg) Summary • Diet plays an important role in a person’s health, appearance, energy, and performance as well as affecting results from exercise and overall wellbeing. • A proper nutritional background is an essential component to being a well-rounded fitness professional. • However, the fitness professional should not instruct clients on the use of diet to treat illness or high-risk cases.