Transcript NORMAL NUTRITION NURP 102 ANDERSON

Chapter Six: Metabolism and
Energy Balance
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Define metabolism, anabolism and catabolism
Explaining what is meant by the “protein
sparing action” of carbo.
Trace the energy release, building and
storage steps of the energy nutrients.
When are amino acids used for energy?
How do excesses of the energy nutrients
contribute to body fat.
Metabolism and Energy Balance
cntd.
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Describe two ways in which the body
spends energy
Identify some of the factors that
influence basal metabolism
Estimate a day’s energy (kcaloric) needs
Identify how fasting or starvation
negatively affects the body
Metabolism
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Metabolism defined: the sum total of
all chemical reactions in the body
Metabolic Roles of the organs:
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Digestive organs: Digestion and
Absorption (rapid cell turnover)
Liver: most active metabolic organ—
metabolizes, packages, stores, & ships
nutrients
Pancreas: secretes dig juices and insulin
Metabolic organs, cntd.
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Pancreas, cntd.: regulates body use of
glucose
Heart & Blood Vessels: transport nutrients
and oxygen
Kidneys: Filters waste products; regulates
blood pressure; converts Vit D to active
form
Body’s Energy Metabolism
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Basic Units of Energy Metabolism:
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Carbohydrate: Glucose
Lipids: Glycerol & Fatty Acids
Proteins: Amino Acids
Results of catabolic reactions—releases
energy—breakdown of compounds
Results of anabolic reactions—uses
energy—building of body compounds
Metabolic Reactions
Catabolic and Anabolic Reactions
Involving Energy Nutrients
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Carbohydrate:
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Glucose used as energy
Glucose converted to glycogen for energy storage
Excess glucose converted to fat
Fats: Triglycerides
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Glycerol & Fatty acids used for energy
Glycerol used for energy or can be converted to
glucose (5% of triglycerides) through process of
gluconeogenesis--inefficient source of glucose
Release of Energy, cntd.
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Proteins
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Amino acids used to maintain, replace and
build new cells
Amino acids can be converted to glucose—
not recommended but can be a back-up
system (90% availability) through the
process of gluconeogenesis
Body’s Energy Budget
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Feasting: Excess of any energy nutrient
can lead to weight gain
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Glucose  Glycogen  Fat
Fat  Fatty Acids/Glycerol  Fat
Protein  Amino Acids  Fat
Fasting/Starvation:
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Body reacts the same to fasting or
starvation
Energy Budget, cntd.
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Ketone formation:
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Liver Glycogen used first  Amino
Acids & Glycerol second
After a few days the body uses fatty acid
fragments from catabolism to form ketones
Ketones can provide fuel for the brain and
nervous system
Metabolic rate slows to conserve energy
Hazards of Fasting
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Wasting of lean body tissue
Impairment of disease resistance
(antibodies depleted)
Lowering of body temperature
Disturbances of the body’s salt and
water balance
Weight Reduction
Recommendations
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Moderate energy restriction
promotes a greater rate of weight
loss, more fat loss, and retains lean
tissue
Maintaining Carbo intake protects
protein from being used to make
glucose—protein sparing fast
Measuring Kcalorie Needs
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Two Ways Energy is Used
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Fuel for Basal Metabolism (minimum
needed for vital body processes) 2/3 of
daily kcalories
Fuel for Voluntary Activities (more control
over this usage) 1/3 of daily kcalories
Metabolic influences, cntd.
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Factors Affecting Basal Metabolic Rate
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Physical activity
Age
Lean Body Mass
Pregnancy
Height
Fever
Thyroid
Malnutrition (low kcalorie intake)
Estimation of Kcalorie Needs
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Change pounds to Kilograms (Pounds / 2.2 = kg)
Multiply Weight in Kilograms by 1 for men and 0.9
for women to find kcalories used in one hour
Multiply kcalories used in one hour by 24 (hours in
a day)
Multiply activity factor* by basal metabolic energy
(determined in #3) to find total daily kcaloric
needs.
*You must determine at which of the five activity
levels you are. (Most effective way to increase
energy needs)
Estimating Energy Needs
MALE
FEMALE
160/2.2 = 72.7 kg 160/2.2 = 72.7
72.7 x 1=72.7 kcal. 72.7 x .9=65.4 kcal.
72.7 x 24 = 1744.8 65.4 x 24 = 1570
Kcal/day for BM
Kcal/day for BM
Light Activity Factor Light Activity Factor
(1.6)
(1.5)
1744.8 x 1.6 = 2792 1570 x 1.5 = 2355
Problems with Ketosis
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Metabolism Slows Down
Most of Weight Loss is water, glycogen, and
lean muscle mass
Excessive water loss = dehydration
May cause mineral imbalances
Risk of hypoglycemia and metabolic acidosis
During pregnancy, can cause brain damage to
the fetus
Possible Hazards of High Protein,
Low Carbohydrate Diets
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Too low Carbs intake can lead to ketosis
Excessive fat, especially saturated fat, and
cholesterol intake
Very low in fiber, potassium and
phytochemicals
Does not provide a balance of nutrients
Too low in kcalories
May stress kidneys
May lead to calcium loss
Practice test questions
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What energy nutrients are digested in
the small intestine?
Water-soluble nutrients are released
into what transport system?
What are sources of glucose if it is not
available from dietary carbohydrate?
Test Questions
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1. One of the functions of the colon is to
reabsorb:
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a. Water
c. Nutrients
b. Vitamins
d. Lymph
2. Of the following, which nutrient takes the
longest to digest?
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a. Fat
c. Vitamin C
b. Sugar
d. Iron
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3. Three factors that affect the body’s
basal metabolism are:
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A. Weight, fever, and environmental
temperature
B. Fever, body composition, and altitude
C. Height, weight, and energy intake
D. Age, body composition and fever
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4. Carbohydrates are called “protein
sparers” because the presence of an
adequate amount:
A. prevents the use of protein for energy
B. Conserves essential fatty acids
C. Prevents protein from being converted to
fat
D. None of the above