Module 6 - Feasting, fasting part 2 Flashcards
What does metabolism favour in times of feasting
Fat formation, this can be done using all macronutrients, however, the most direct and efficient process occurs from dietary fat
Process of fat intake to body fat
Most direct and efficient. Involves hydrolysis of TG by lipoprotein lipase in the bloodstream, where it can either be metabolized for energy or reassembled into TG for storage in adipose cells
What does a fat cell look like
Majority of it is a large central globule of pure fat
When their is an excess of all macronutrients, what does the body do first
Firstly, carbs ingested first replace glycogen stores or is oxidized and used for energy
Then any further excess carb are converted to fat and excess fat ingested goes to fat
(So any ingested fat at this point is promoted towards storage and not oxidation)
What is fasting as opposed to starvation.
Fasting refers to when someone chooses not to eat whereas starvation is when a person has no choice not to eat
What happens in the initial first days of fasting
Glucose and fatty acids are broken down into acetyl CoA which enters energy pathway. During these days, body protein provides 90 percent of the glucose needed, the other 10 are provided by glycerol
What is the hormone sensitive lipase
Enzyme inside fat cells that respond to hormones such as epinephrine and glucagon which indicate need for fuel. Then TG stores are broken down and the FA are used to produce energy within the cell or release with glycerol in the bloodstream
One pound of body fat provides how many calories
3500 kcalories
What happens with fasting beyond glycogen depletion
Gluconeogenesis. Where body will begin to break down protein to synthesize glucose for brain and nervous system. Also, liver converts fats to ketone bodies which is an alternative energy source for the brain
What is the main contributor energy after a few days of feasting
Fat. Rate doubles which gives more glycerols to make glucose. Acetyl CoA can also be used to make ketone bodies which is also fuel for brain
What are ketone bodies
Water soluble molecules produced by the liver from FA during periods of low food intake
How are ketone bodies formed
During fatty acid oxidation, instead of acetyl CoA going through TCA cycle, 2 acetyl CoA combine when the CoA are removed which will lead to the formation of a ketone body
Why are too many ketone bodies in the body dangerous
They are acidic and can lower pH, they create fruity odour on breath and ketosis will cause loss of appetite
What does prolonged glucose deprivation cause
Death. Because even if the person still had body fat, the proteins will be used up too much and eventually major organs will be affected by protein loss
How is energy conserved during starvation
Hormones store metabolism, their is a reduced energy output, we can live 2 months with water
