Download MBBS (Bachelor of Medicine and Bachelor of Surgery) Latest The Feed Fast Cycle Lecture PPT
THE FEED-FAST CYCLE
OVERVIEW OF THE ABSORPTIVE PHASE
The absorptive (well-fed) state is 2-4 hrs period after
ingestion of a normal meal
During this interval, transient increases in plasma glucose,
amino acids and TAG is seen
Islet tissue of pancreas responds to elevated level of
glucose with increased secretion of insulin and decreased
secretion of glucagon
The elevated insulin/glucagon ratio and the ready
availability of circulating substrates make the absorptive
state an anabolic period characterized by increase
synthesis of TAG and glycogen as well as increased
synthesis of protein
During this absorptive period, virtually all tissues use
glucose as a fuel, and metabolic response of the body
is dominated by alterations in the metabolism of liver,
adipose tissue, skeletal muscle and brain
LIVER:NUTRITION DISTRIBUTION
CENTER
The liver is uniquely situated to process and distribute
dietary nutrients because the venous drainage of the
gut and pancreas passes through the hepatic portal
vein before entry in to general circulation
Thus, after a meal, the liver is bathed in blood
containing absorbed nutrients and elevated levels of
insulin secreted by pancreas
During the absorptive phase, the liver takes up
carbohydrates, lipids and most amino acids
ADIPOSE TISSUE: ENERGY STORAGE
DEPOT
Adipose is second only to liver in its ability to
distribute fuel molecule
In a 70 kg man, white adipose tissue weighs around 14
kg or about half as much as total muscle mass
Nearly the entire volume of each adipocyte in WAT
can be occupied by anhydrous,calorically dense TAG
SKELETAL MUSCLE
Skeletal muscle accounts for nearly 40% of the body
mass in individuals of healthy weight and it can use
glucose, amino acids, and ketone bodies as fuel.
Skeletal muscle is unique in being able to respond to
substantial changes in the demand for ATP that
accompanies muscle contraction
At rest, muscle accounts for 25% of oxygen
consumption of the body ,whereas during vigorous
exercise ,it is responsible for up to 90% of total
oxygen consumed
BRAIN
Although contributing only 2% of adult
weight, brain accounts for a consistent 20%
of basal oxygen consumption of the body
at rest
In the fed state, brain exclusively uses
glucose as a fuel ,completely oxidising
140g/day to carbon dioxide and water
OVERVIEW OF FASTING STAGE
Fasting begins if no food is ingested after the absorptive
period
It may result from inability to obtain food, the desire to
lose weight or clinical situation in which an individual can
not eat
In the absence of food, plasma level of glucose falls,
triggering a decline in insulin secretion and increase in
glucagon, epinephrine and cortisol secretion
Decrease insulin/glucagon ratio and decreased availability
of circulating substrates make the postabsorptive period a
catabolic period characterized by degradation of glycogen,
TAG and protein
Starve cycle is divided in two four stages:
Early fasting (4-16 hrs after food)
Prolonged Fasting (16-48 hrs after food)
Starvation (2-3 days without food)
Prolonged starvation (>5 days without food)
This post was last modified on 30 November 2021