I do not have a scientific background, but I do read a lot, reading knowledgeable people. I do have a hole in my knowledge. My thinking has been that cells are fueled by either glucose or ketones. Then I read somewhere that the ultimate fuel molecule for the cells is something called ATP.
However two people whom I respect, one a friend who is a doctor, and my son who has a degree in Biology and a master's in computer science have told me that everything, even fat, is converted into glucose to fuel our cells, glucose being the final fuel.
So as you can see I am really mixed up. This knowledge will help me formulate a diet as well as help others. thank you.
asked byeric_9 (4319)
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on December 24, 2011
at 12:42 PM
This is not true.
Starch is converted to glucose. Glucose is broken down by glycolysis to pyruvate which then goes into the mitochondria to be converted to Acetyl CoA.
Fatty acids (long and medium chain) go into the mitochondria and are broken down by a set of reactions commonly referred to as the "Fatty Acid Spiral" or beta-oxidation. The resulting molecules are Acetyl CoA.
Acetyl CoA then feeds into the Kreb's Cycle aka TCA cycle which produces some ATP and NADH and FADH2. The NADH and FADH2 that are produced in Krebs (and some in precursor steps) feed into what's called the Electron Transfer Chain. It is the ETC where most of the ATP is produced.
So, Acetyl CoA is the common molecule in the metabolism of glucose and fatty acids, and some amino acids from protein. Amino acids apparently feed into Krebs in different places. Note that the acetoacetylCoA is ketone formation.
If you paid for your son's education, you should ask for some money back ;-) Seriously ... I have a degree in biology and teach chemistry at the college level. If your son learned that all macros are turned to glucose there's a serious problem with that. :(
on December 24, 2011
at 12:45 PM
At rest your body can run on either glucose, ketones or free fatty acids which are all converted into ATP before being used for fuel(your usually burning a mixture of fat and carbohydrates). The higher intensity you go the more your body leans towards burning carbs but this can be manipulated with training and diet.
Fat can't directly be converted to glucose but the backbone(glycerols) of stored fats(triglycerides) can be converted and supply the body with glucose. Protein and lactate can both provide substrate for gluconegensis(glucose conversion).