chapter six: metabolism and energy balance define metabolism, anabolism and catabolism explaining...
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Chapter Six: Metabolism and Energy Balance 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. 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 Metabolism defined: the sum total of
all chemical reactions in the body Metabolic Roles of the organs:
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. 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 Basic Units of Energy Metabolism:
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
Catabolic and Anabolic Reactions Involving Energy Nutrients Carbohydrate:
Glucose used as energy Glucose converted to glycogen for energy
storage Excess glucose converted to fat
Fats: Triglycerides 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. Proteins
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 Feasting: Excess of any energy
nutrient can lead to weight gain Glucose Glycogen Fat Fat Fatty Acids/Glycerol Fat Protein Amino Acids Fat
Fasting/Starvation: Body reacts the same to fasting or
starvation
Energy Budget, cntd. Liver Glycogen used first Amino
Acids & Glycerol second Ketone formation:
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 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
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 Two Ways Energy is Used
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. Factors Affecting Basal Metabolic Rate
Physical activity Age Lean Body Mass Pregnancy Height Fever Thyroid Malnutrition (low kcalorie intake)
Estimation of Kcalorie Needs1. Change pounds to Kilograms (Pounds / 2.2 = kg)2. Multiply Weight in Kilograms by 1 for men and
0.9 for women to find kcalories used in one hour3. Multiply kcalories used in one hour by 24 (hours
in a day)4. 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 FEMALE160/2.2 = 72.7 kg 160/2.2 = 72.772.7 x 1=72.7 kcal. 72.7 x .9=65.4 kcal.72.7 x 24 = 1744.8 65.4 x 24 = 1570Kcal/day for BM Kcal/day for BMLight Activity Factor Light Activity Factor(1.6) (1.5)1744.8 x 1.6 = 2792 1570 x 1.5 = 2355
Problems with Ketosis 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 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 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 1. One of the functions of the colon is
to reabsorb: a. Water b. Vitamins c. Nutrients d. Lymph
2. Of the following, which nutrient takes the longest to digest? a. Fat b. Sugar c. Vitamin C d. Iron
3. Three factors that affect the body’s basal metabolism are: A. Weight, fever, and environmental
temperature B. Fever, body composition, and
altitude C. Height, weight, and energy intake D. Age, body composition and fever