Fat Flashcards
Two main reducing equivalents in cells and how much ATP they provide, and what is the ratio when oxidizing purely fatty acids ?
NADH - 2.5ATP
FADH - 1.5ATP
NADH:FADH2 is 2:1
how a ketogenic diet might affect oxygen utilization at a given power output during a 50 km time trial
Because you are relaying more on fat for energy supply exercise a the same power output you need to consume more oxygen, as less NADH is produced, thus you are less efficient.
Difference between low carb high fat diet and ketogenetic diets?
LCHF = >60%fat, <25% CHO
Keto - <50g CHO
Is a high fat diet better for performance ?
If at a low intensity yes because it causes you to use fat as a more sustained energy source.
But not if performance is the goal.
This can be due to the Highs fat increased pyruvate production leading to more acetyle-CoA. This increases PDH which makes pyruvate dehydrogenase inactive, thus slowing the metabolism.
Or by increased citrate during exercise which inhibit PFK, CHO oxidation speed limiter.
After starting a high fat diet how quickly does this elicit a metabolic shift ?
5 Days
As exercise intensity increases there is a reduction in the overall rate of fat oxidation. Why could this be ?
- Slow mobilization of FA from adipose tissue/skeletal muscle (lipolysis)?
- Transport of FA into the muscle cell?
- Transport of FA into mitochondria?
- Oxidation of FA in β-Oxidation?
What would be the effect of taking ketone salts, which increase β-hydroxybutyrate on NADH, FADH, overall exercise economy and performance ?
Taking the ketone salts will result in the reverse reaction of ketogenesis to occur. This causes 1 NADH and 2 acetyl COA to form
acetyl-CoA enters TCA cycle and spins twice as there as two. this produces 6 NADH and 2 FADH2.
This will mean that you are more economical that a full ketogenetic diet as you NADH/ FADH ratio per molecule is 3.5: 1. But still less than carbohydrate diet.
Performance wise you are going to be using less overall VO2 as a % of your max, but you can kick a bit as well now. But you are still working harder than you would be with carb intakes.
Only relevant for low intensity endurance events. As it spares glycogen massively.
When oxidising glucose what is the NADH:FADH2 ratio ?
5:1 in favor of NADH. Produced during the glycolic and the TCA cycle.
What is the effect of high fat diets, and hence greater fatty acid on expression of better fat metabolism enzymes ?
Fatty acids simulate PPAR, a transcription factors which creates CD36, CPT1, FABP and PDK4.
CD36, CPT1 and FABP are drivers of fat metabolism so helps to use this during exercise
PDK4 impairs glucose metabolism, by inhibiting pyruvate dehydrogenase during glycolysis, resulting in energy required elsewhere.
What body states indicate ketosis ?
Ketosis:
Serum [ketone] 1-3 mmol/L, low insulin and glucose
Brain predominantly relies on glucose for fuel
Liver glycogen ↓ = blood glucose ↓ = ↓ fuel for the brain
Fatty acids are converted to ketones (via acetyl CoA)
Ketones can cross the BBB (fatty acids cannot)
Explain how a ketogenic diet might affect performance during the time trial.
Because you are having to work at a higher percentage of VO2max, due to a greater oxygen uptake being required to oxidize fat, you will not be able to switch up to a higher exercise intensity because or either a low level on carbs.
If you have carbed up you still will not be able to do this because due to the keto diet you have less activation of PDH (pyruvate dehydrogenase). This is because acetyl-COA build up from using fat impairs this.
