Transcript Nutrition - the Health Science Program

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
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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
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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)
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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.
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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
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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
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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
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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?
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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.