Download Nutritional Principles and Energy Metabolism.

Subtopics: ENERGY BALANCE
AND METABOLIC RATE.

1st Law of Thermodynamic:
Energy is neither created nor destroyed, but can
be transferred and converted from one form to
another.

Energy balance between caloric intake and
energy output:
a) If caloric content in the food ingested < energy
output (balance is negative), endogenous stores are
utilized. Glycogen, body protein, and fat are
catabolized, and the individuals loses weight.
b) If caloric value of the food intake
exceeds energy loss due to heat &
work, and the food is properly
digested & absorbed (balance is
positive), then energy is stored and
the individual gains weight.

Animal organisms oxidizes carbohydrates,
proteins, and fats; producing principally CO2,
H2O and energy necessary for life processes.

The complex, slow, stepwise oxidation
process are called catabolism (metabolism).

Catabolism function – liberates energy in
small, usable amount.

Uses of energy (produced from catabolism):
i) Maintaining body functions.
ii) Digesting and metabolizing food.
iii) Thermoregulation.
iv) Physical activity.

Energy storage:
a) in the form of special energy-rich phosphate
compounds (ATP).
b) in the form of proteins.
c) in the form of fats.
d) in the form of glycogen.

Energy liberated appears as:
Energy output = External work + Energy
storage + Heat.

What is metabolic rate.?
The sum of all the energy-requiring
biochemical reactions over a given time
interval.

Factors affecting the metabolic rate ::: muscular exertion during or just before
measurement.
:: recent ingestion of food.
:: high or low environmental temperature.
:: height, weight, and surface area.
:: sex.
:: age.
:: growth.
:: reproduction.
:: lactation.
:: emotional state.
:: body temperature.
:: circulating levels of thyroid
hormone.
:: circulating epinephrine and
norepinephrine levels.

Basal Metabolic Rate (BMR):
a) Determined at rest in a room at a
comfortable temperature in the
thermoneutral zone, 12 to 14 hours after
the last meal.
b) Value falls about 10% during sleep and up to
40% during prolonged starvation.
c) Rate during normal daytime higher than
BMR (because of muscular activity and food
intake).
d) Large animals have higher absolute BMRs,
but the ratio of BMR to body weight in small
animals is much greater (variable: body
surface area).