NASM Chapter 17 Nutrition

Definition

  • Nutrition
    The process by which a living organism assimilates food and uses it for growth and repair of tissues.

STANDARDS OF PRACTICE AND SCOPE OF PRACTICE: PERSONAL TRAINERS VERSUS LICENSED DIETICIANS

  • Personal trainers should be familiar with the concepts of nutrition.
  • Integrating nutritional
  • strategies with exercise will help clients achieve their desired outcomes. It is important, however, to recognize and respect the scope of practice of each professional field.
  • 46 states have specific laws that explicitly define scope and practice for nutrition and dietetics professionals, and performing these duties without a license could be considered illegal.
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Daily Energy Needs

  • Calorie (lower case “c”)
    amount of heat energy required to raise temp of 1 gram of water 1C.
  • Calorie (upper case C) 
    Unit expression of energy equal to 1,000 calories. Amount of heat energy required to raise 1 KG or liter of water 1C or kilocalorie.
  • Kilocalorie
    equal to 1,000 calories, raise 1kg of water 1 degree C.
  • Estimated total energy expenditure (TEE), also referred to as total daily energy expenditure (TDEE)
    defined as the amount of energy (calories) spent, on average, in a typical day. TEE is actually the sum total of three different energy components:
  •  Resting metabolic rate (RMR)
    The amount of energy expended while at rest; represents the minimal amount of energy required to sustain vital bodily functions such as blood circulation, respiration, and temperature regulation. RMR typically accounts for 70% of TEE.
  • Thermic effect of food (TEF)
    The amount of energy expended above RMR as a result of the processing of food (digestion) for storage and use. TEF typically accounts for approximately 6–10% of TEE.
  • Energy expended during physical activity
    The amount of energy expended above RMR and TEF associated with physical activity. Physical activity accounts for approximately 20% of TEE.

Resting metabolic rate

  • RMR Accounts for 70% of total daily energy expenditure in sedentary person.
  • Affected by wide variety of factors including age, sex, genetics, hormonal changes, body size, body comp.
  • 27 million Americans have thyroid related disorders.
  • Cardiovascular medicationss can reduce RMR from 4 to 12%.
  • Chemo can reduce RMR from 6 to 11%.
  • Long term use of growth hormone increases RMR by 12%.
  • Thyroid meds and hypothyroidism can increase RMR by 17%.
  • To avoid declines in resting metabolism individuals should be encouraged to avoid starvation diets that could lead to wasting of skeletal muscle and instead be encouraged to build and maintain muscle for active living.
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Thermic effect of food

  • Process of digestion requires energy, increase in energy expenditure after meal is called thermic effect of food (TEF) 6-10% of total energy expenditure

Estimating Total Daily Energy Expenditure

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  • Even the most commonly used formulas can have up to a 20% variance in overestimating
    or underestimating resting metabolism and total energy expenditure

Protein

  • Protein
    Amino acids linked by peptide bonds.
  • The primary function of protein is to build and repair body tissues and structures. It is also involved in the synthesis of hormones, enzymes, and other regulatory peptides. Additionally, protein can be used for energy if calories or carbohydrate are insufficient in the diet

Structure of Protein

  • Proteins are made up of amino acids linked together by peptide bonds. The body uses approximately 20 amino acids to build its many different proteins
  • There are two general classes of amino acids: essential and nonessential
  • Essential amino acids cannot be manufactured in the body (or are manufactured in insufficient amounts); therefore, they must be obtained from the food supply or some other exogenous source. (8 total aminos in this catagory)
  • nonessential aminos are termed so because the body is able to manufacture them from dietary nitrogen and fragments of carbohydrate and fat
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Digestion, Absorption, and Utilization

  • Proteins must be broken down into the constituent amino acids before the body can use them to build or repair tissue or as an energy substrate
  • Proteins encounter HCL in stomach which uncoils(denatures) protein so that digestive enzymes can begin dismantling peptide bonds. The enzyme pepsin begins to cleave protein strand into smaller polypeptides(strands of several amino acids) and single amino acids.
  • As protein fragments leave stomach and enter small intestine, pancreatic and intestinal proteases(protein enzymes) continue to dismantle the protein fragments
  • Resulting dipeptides, tripeptides, and single amino acids are then absorbed through the intestinal wall into enterocytes and released into the blood supply to the liver.
    Once in bloodstream, free-form amino acids have several possible fates: they can be used for protein synthesis(building and repairing tissues or structures), immediate energy, or potential energy(fat storage).
  • Amino acids are first deaminated(stripped of amine group), allowing remaining carbon skeleton to be used for production of glucose or ketones to be used for energy.
  • Removed amine group produces ammonia, which is converted to urea in the liver and excreted as urine by the kidneys.
  • If intake exceeds need for synthesis, then proteins are deaminated, carbon fragments stored as fat
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Protein in Foods

  • Dietary protein is the delivery vehicle for amino acids
  • If food supplies all essential amino acids in appropriate ratios it is called complete protein.
  • If food source is low or lacking in one or more essential amino acids it is called incomplete protein.
  • Terms used to rate dietary protein include
  • 1. protein efficiencyratio (PER)
  • 2. net protein utilization (NPU)
  • 3. biologic value (BV)
  • Biologic value (BV) measure frequently used when discussing protein sources, BV is measure of protein quality, how well it satisfies body’s essential amino acid needs. ( frequently used when discussing protein sources in popular media and by supplement manufacturers.)
  • Protein source with higher score provides amino acid profile that is more closely related to needs of the human body.
  • Major sources of complete proteins are animal sources, dairy and meats.
  • Sources of incomplete protein include grains, legumes, nuts, seeds, and other vegetables.

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  • If one does not eat adequate amounts of carbohydrate and fat (as is often seen in low-calorie or low-carbohydrate diets or during physique-competition preparation), more protein will be used for energy by default.

Negative Energy Balance

  • For clients pursuing body-fat reduction, body-fat loss goals require that a caloric deficit be maintained until the goal is reached.
  • During a negative energy balance, amino acids are used to assist in energy production, a term referred to as gluconeogenesis.
  • The amount of lean body mass lost in persons in a negative energy balance can be reduced by increasing the amount of protein in the diet, leading to a more rapid return to nitrogen balance.

Protein and the Bodybuilder

  • Bodybuilders during positive energy balance (off-season) should follow the same protein recommendations as strength athletes. However, during negative energy balance
    (used to create competition-level body-fat percentages), protein requirements may dramatically increase.
  • Competitive levels of body fat are generally unhealthy and impossible to maintain for prolonged periods.
  •  In fact, it appears that carbohydrate
    (1 g per kg or 0.5 gram per pound), not protein, consumed within an hour after heavy resistance training inhibits muscle-protein breakdown, resulting in a positive protein balance

How much protein is required to build muscle

  • Skeletal muscle is approximately 72% water, 22% protein, and 6% fat, glycogen, and minerals, and 1 pound of muscle tissue contains approximately 100 g of protein.
  • Theoretically, an athlete would have to ingest an extra 14 g of protein per day, although most experts believe the single most important factor in gaining lean mass (along with resistance training, of course) is consuming adequate calories.
  • Therefore, to ensure the body has suffi cient energy for lean mass accretion, consume an additional 200 to 400 calories daily (3 to 5 calories per kg or 1.5 to 2.5 calories per pound per day) above maintenance requirements in addition to consuming a little extra protein (approximately 2 ounces of lean meat).

Protein’s Effect on Satiety

  • As with all macronutrients, protein activates specific satiety mechanisms and may be more satiating
    than fat and carbohydrate.
  • Individuals seeking fat loss may benefit from the satiating properties of protein to feel full and energized throughout the day. This can assist clients in program adherence
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  • a small person losing fat (or hypocaloric) and exercising using strength and aerobic training may have a high percentage of protein (around 25%) but still fall in the appropriate range of absolute protein (1.2 to 1.7 g/kg/day).

Negative Side Effects Associated with Chronic Use of High-Protein Diets

  • A high-protein diet is typically defined as one that consists of more than 35% of total caloric intake from protein, or three times the protein RDA for athletes.
  • there is a need for greater fluid consumption when consuming large quantities of protein. Protein requires approximately seven times the water for metabolism than carbohydrate or fat.
  • Low-carbohydrate consumption typically accompanies high-protein diets (especially for weight loss), which can lead to decreased glycogen stores, inhibition of performance, and possible dehydration.
  •  Because dehydration of as little as 3% can impair performance, athletes and active individuals ingesting extra protein should weigh themselves regularly to ensure they are properly hydrated.
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Carbohydrates

  • Carbohydrates
    Neutral compounds of carbon, hydrogen, and oxygen (such as sugars, starches, and celluloses), which make up a large portion of animal foods.
  • The definition of sugar, as it would appear on a food label, is any monosaccharide or disaccharide
  • A monosaccharide is a single sugar unit, many of which are connected to make
    starches (the storage form of carbohydrates in plants) and glycogen (the storage form
    of carbohydrates in humans).
  • Monosaccharides include glucose (commonly referred to as blood sugar), fructose (or fruit sugar), and galactose.
  • Disaccharides (two sugar units) include sucrose (or common sugar), lactose (or milk sugar), and maltose.
  • Polysaccharides are long chains of monosaccharide units linked together and found in foods that contain starch and fiber. These foods are often called complex carbohydrates and include starch found in plants, seed, and roots.
  • Carbohydrates are a chief source of energy for all body functions and muscular
    exertion.

Digestion, Absorption, and Utilization

  • The principal carbohydrates present in food occur in the form of simple sugars, starches, and cellulose.
  • Simple sugars, such as those in honey and fruits, are very easily digested.
  • Double sugars, such as table sugar, require some digestive action but are not nearly as
    complex as starches, such as those found in whole grain.
  • Starches require prolonged enzymatic action to be broken down into simple sugars (i.e., glucose) for utilization.
  • The rate at which ingested carbohydrate raises blood sugar and its accompanying effect on insulin release is referred to as the glycemic index (GI)
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Role of Fiber in Health

  • Higher fiber intake is associated with lower incidence of heart disease and certain types of cancer.
  • Insoluble fiber does not absorb or dissolve in water passes through the digestive tract close to its original form.
  • Insoluble fiber offers many benefits to intestinal health, including a reduction in the risk and occurrence of colorectal cancer, hemmrrhoids, and constipation.
  • Additional benefits of fiber include:
  • 1. Provides bulk in the diet, thus increasing the satiety value of foods.
  • 2. Some fi bers also delay the emptying of the stomach, further increasing satiety (78).
  • 3. Prevents constipation and establishes regular bowel movements.
  • 4.  May reduce the risks of heart and artery disease by lowering blood cholesterol.
  • 5. Regulates the body’s absorption of glucose (diabetics included), perhaps because
    fiber is believed to be capable of controlling the rate of digestion and assimilation of carbohydrates.
  • 6. High-fi ber meals have been shown to exert regulatory effects on blood glucose levels
    for up to 5 hours after eating.

Carbohydrate Intake Performance

  • 6 and 10g/kg/day of carbs is recommended. 45 to 65% of total caloric intake. Complex carbs constitute majority of calories.
  • Before exercise consume high carb meal 2 to 4 hours. Glycogen stores are lowered by as much as 80% in the mornings.
  • Endurance athletes consume between 30 and 60g of carbs every hour to maintain blood glucose levels.
  • One hour of intense cycling was improved by 12% with consumption of 53 ounces of water containing 79g of carbs.
  • Timing of carbs important for maximizing recovery, recommended consuming 1.5g per KG of carbs within 30 mins of completing exercise to maximize glycogen replenishment. Delaying intake by even 2 hours can decrease total muscle glycogen synthesis by 66%.
  • PWO environment hasten glycogen repletion as a result of increased blood flow to muscles and increased sensitivity of cells to effects of insulin.
  • For exercise lasting more than 1 hour, carbohydrate feedings during exercise can help supply glucose to working muscles whose glycogen stores are dwindling. This technique also maintains blood glucose levels, increasing time to exhaustion by 20 to 60 minutes
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Lipids

  • Lipids are a group of compounds that include triglycerides (fats and oils), phospholipids, and sterols. Of the lipids contained in food, 95% are fats and oils. In the body, 99% of the stored lipids are also triglycerides.
  • Structurally, triglycerides are three fatty acids attached to a glycerol backbone

Fatty Acids

  • Fatty acids may be saturated or unsaturated
  • Unsaturated fatty acids maybe further classified according to their degree of unsaturation.
  • If the fatty acid has one double bond in its carbon chain, it is called a monounsaturated fatty acid
  • If there is more than one point of unsaturation, it is classifi edas a polyunsaturated fatty acid
  • Saturated and trans Fats increase risk factors for heart disease because they raise bad cholesterol levels (Low-density lipoproteins; LDL)
  • Mono and Poly Unsaturated fats are associated are considered to have favorable effects on blood.

Function of Lipids

  • Lipids (or fats) are the most concentrated source of energy in the diet. One gram of fat yields approximately 9 calories when oxidized, furnishing more than twice the calories per gram of carbohydrates or proteins.
  •  Fats are involved in the following:
  • ■ Cellular membrane structure and function
  • ■ Precursors to hormones
  • ■ Cellular signals
  • ■ Regulation and excretion of nutrients in the cells
  • ■ Surrounding, protecting, and holding in place organs, such as the kidneys, heart, and liver
  • ■ Insulating the body from environmental temperature changes and preserving body heat
  • ■ Prolonging the digestive process by slowing the stomach’s secretions of hydrochloric acid, creating a longer-lasting sensation of fullness after a meal
  • ■ Initiating the release of the hormone cholecystokinin (CCK), which contributes to satiety

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  • Throughout the day, triglycerides are constantly cycled in and out of tissues, including muscles, organs, and adipose
  • Distribution Range for fat intake for an adult is 20 to 35% of total caloric intake
  • Athletes are recommended to consume 20 to 25% of total calories from fat,
  • there appears to be no health or performance benefit to consuming less than 15% of energy from fat
  • Medium Chained Triglycerides Do not increase performance or weight loss
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Water

  • Sedentary men and women should consume on average 3.0 L (approximately 13 cups) and 2.2 L (approximately 9 cups) of water per day
  • Those participating in a fat-loss program should drink an additional 8 ounces of water for every 25 pounds they carry above their ideal weight.
  • Water intake should also be increased if an individual is exercising briskly or residing in a hot climate.
  • it constitutes approximately 60% of the adult human body by weight.
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BASIC NUTRITIONAL GUIDELINES FOR ALTERING BODY COMPOSITION

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  • For Lean Body Mass Gain:
  • ■ Eat four to six meals a day. Insulin response to a meal stimulates protein synthesis.
  • ■ Spread protein intake throughout the day to take advantage of the previous tip.
  • ■ Keep in mind the postworkout window of opportunity. Ingestion of protein and carbohydrate within 90 minutes of a workout will increase recovery and protein synthesis, maximizing gains. This may be most easily accomplished with a liquid meal-replacement formula that can be absorbed quickly owing to being predigested. Food may take several hours to digest and absorb, missing the window.
  • ■ Do not neglect the importance of carbohydrate and fat. It takes more than protein to increase lean body mass.
  • Although gym lore places recommendations as high as 2 g of protein per pound of body weight, the scientifically based recommendation for strength athletes range from 0.5 to 0.8 grams of protein per pound
    (1.2 to 1.7 g per kg)
  • Fitness professionals should discourage overly restrictive programs advocating less than 1,000 to 1,200 calories per day, and support safe, maintainable weight loss by means of more healthful eating, smaller portions, and increased activity

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