BIOC Lecture 5: Fasting Flashcards
What are by far the greatest proportion of our stores?
Fats
What is the problem with using proteins as an energy store?
Their main roles are impaired
What is the compensation for falling glucose levels during long term starvation?
Ketone bodies and an increase in fatty acids in the blood and a further shifting of tissues from using glucose to using fatty acids
Where do ketone bodies come from?
Fat/fatty acids
What happens to metabolic fuels after 12 hours starvation?
Approximately same coming from glucose and fat (41% + 46%), small amount from protein (13%)
What happens to metabolic fuels after 60 hours starvation?
Using less glucose (6%), prominently fat (75%) and increased protein (19%)
What are metabolic fuels?
Glucose, fat, protein
What are plasma fuels?
Ketone bodies, glucose, fatty acids
What happens to plasma fatty acids during long term starvation?
Small increase
What happens to plasma glucose during long term starvation?
Small decrease but bigger proportionally to fatty acids increase
What happens to ketone bodies during long term starvation?
HUGE increase
Are fatty acids good transport molecules?
NO
Are ketone bodies good transport molecules?
YES
What is the biggest store of fuel?
Fat (15kg)
What is the next biggest store of fuel?
Protein (6kg) - it has roles so we don’t want to get rid of it
What is the smallest store of fuel?
Glycogen (0.2kg)
What is the order of prominence of circulating fuels from most to least?
Glucose, TAGs, FFA’s
What happens to brain mass after long term starvation?
Very little change (7% loss)
What happens to the lung and liver mass after long term starvation?
Moderate/high loss (30%)
What happens to the heart and muscle mass after long term starvation?
High loss (40%)
What happens to kidney and pancreas mass after long term starvation?
High loss (50%)
What is the order of priority from high to low in organs that are maintained during starvation?
Brain, Liver, Lungs, Heart, Muscle, Kidney, Pancreas
Where does glucose come from during long term starvation?
From protein, ketone bodies spare glucose
What are other body effects from long term starvation?
Reduced metabolic rate, change in thyroid hormones
What causes death from starvation?
- Loss of organ function
- Decrease in immune system
- Cardiac failure
What is whole body calorimetry?
Measures temperature and CO2 produced - measuring how much energy someone is expending
Dietary intakes typically vary more than what?
Weight
An extra 15g of sugar a day correlates to the gain of what?
About 2.5kg of fat per year
What is there considerable evidence towards?
That each person has a set point
What does RMR vary between, and what is the mean?
4.3MJ/d to 10.5MJ/d, mean of 6.3MJ/d
What accounts for differences in RMR?
Differences in lean mass mostly aswell as fat mass and age
RMR of the same lean mass can vary up to?
32%
Metabolic rate declines with…
Age
What is lean mass associated with?
Protein - higher muscle = higher RMR
