T Nation

The ATP Economy?

This has tickled my brain for a while so I finally decided to post it up here. Give it a look-over and tell me what you think.

I don’t feel like being wordy so I’ll go point form:

When we do “cardio” we generally record our work output in the form of “calories burned”.

“Calories” are a measurement of the heat units that come out of nutrients in a bomb calorimeter.

Is the human body a bomb calorimeter? No.

When we are active are we really burning “calories”? No.

We are “burning” ATP.

So the goal should then be how do we burn the maximum amount of macronutrients with the least amount of ATP?

Then, using that pathway, how do we burn as much ATP as possible to maximize the amount of ingested and stored macronutrients burned?

I dug into my old manuals and found this:

ATP-PC system: 1 ATP per unit of PC

Fast glycolysis: 2 ATP per molecule of glucose or glycogen

Slow glycolysis: 38 ATP per molecule of glucose of glycogen

Fatty acid oxidation: 100 ATP per molecule of glucose or glycogen

Turning that around, we get this:

ATP/PC: 100 ATP = 100 PC

Fast glyc: 100 ATP = 17 molecules glycogen or glucose

Slow glyc: 100 ATP = 2.6 mol’s glyc or gluc

Fatty acid ox: 100 ATP = 1 molecule fatty acid

So no wonder steady-state cardio doesn’t burn much fat. For every “calorie” of ATP burned in a lactic sprint, we burn 17 TIMES as much glycogen reserve as we would with the same amount of work done in a “steady-state” manner.

Then during the next 24-48 hours, while our bodies are at rest, we dip into fat stores to replenish glycogen stores via gluconeogenesis.

Is this right? Is this how it works? I didn’t take biochemistry in college so someone please help me out if my numbers aren’t right.

Thanks,

ElbowStrike

[quote]ElbowStrike wrote:
r.
, we dip into fat stores to replenish glycogen stores via gluconeogenesis.

[/quote]

No, fat CANNOT be converted into glucose. In that instance, iy would be muscle proteins, aka your muscle would be catabolized and the proteins would be converted to glucose through gluconeogenesis.

Carbs are the primary source of glucose, protein a secondary, fat cannot be converted into glucose ever.

[quote]GetSwole wrote:
ElbowStrike wrote:
r.
, we dip into fat stores to replenish glycogen stores via gluconeogenesis.

No, fat CANNOT be converted into glucose. In that instance, iy would be muscle proteins, aka your muscle would be catabolized and the proteins would be converted to glucose through gluconeogenesis.

Carbs are the primary source of glucose, protein a secondary, fat cannot be converted into glucose ever.[/quote]

Exactly. Humans lack the ability to go from Acetyl CoA to glucose; Acetyl CoA is the main product of beta-oxidation of fatty acids. This Acetyl CoA can enter the Citric Acid Cycle or can be used to produce ketones which can then serve as fuel substrates.

[quote]ElbowStrike wrote:

So the goal should then be how do we burn the maximum amount of macronutrients with the least amount of ATP?

[/quote]

Well, we don’t “burn” macronutrients. We “burn” the ATP derived from the carbon skeletons derived from macronutrients.

If you want to burn fuels with the least amount of ATP produced?

Easy. Uncouple ATP production with oxidative-phosphorylation, so that all the energy is lost as heat, and no ATP “fuel” is generated, so more and more substrate is oxidized.

We can do this through the use of metabolic uncouplers, the most popular of which is DNP.

Not the best idea :wink:

[quote]NewDamage wrote:

Exactly. Humans lack the ability to go from Acetyl CoA to glucose; Acetyl CoA is the main product of beta-oxidation of fatty acids. This Acetyl CoA can enter the Citric Acid Cycle or can be used to produce ketones which can then serve as fuel substrates.[/quote]

So beta-oxidation of fatty acids --> acetyl-CoA
Acetyl-CoA --> ketones
ketones + amino acids --> gluconeogenesis?

So a hypocaloric, low-carb, high protein, high fat diet (kind of like the Anabolic Diet) coupled with lactic training would be the “best” for fat loss, theoretically.

Oui? Non?

ElbowStrike

Well, its more like…

beta-oxidation of fatty acids --> acetyl-CoA + reduced nucelotides (NADH and FADH) + H+ ions which can all go through the electron transport chain.

Acetyl-CoA --> combines with oxaloacetate in the citric acid cycle OR if gluconeogenesis is already occurring, oxaloacetate becomes depleted and acetyl coA builds up and then is used to form ketones.

amino acids --> gluconeogenesis or ketogenesis, depending on whether or not its a glucogenic or ketogenic amino

[quote]ElbowStrike wrote:

So a hypocaloric, low-carb, high protein, high fat diet (kind of like the Anabolic Diet) coupled with lactic training would be the “best” for fat loss, theoretically.

Oui? Non?

ElbowStrike[/quote]

Probably depends on what your definition of “high protein” is, as you’d probably wanna keep fat kcal equal to or greater than protein kcal. But that is the basis for those type diets.

This may be a silly question, but as you all know the bulk of the ATP production from Acetyl CoA comes from the electron transfer chain, in which the final electron acceptor is oxygen.

So for any type of fat loss, I’d think that anaerobic work will be more energy inefficient (work efficient per fat loss), which is a good thing for our cutting purposes. Does anyone know if Acetyl-CoA will find itself in the ketone pathway in an anaerobic environment? (NewDAmage’s post suggests that to me, since no oxygen will block the use of the ETC and cause an Acetyl-CoA buildup) I was under the impression that ketone formation mostly occurred due to lack of CHO, in the long term, but can it also be a short term (rapid acting) pathway?

[quote]Lurker27 wrote:
This may be a silly question, but as you all know the bulk of the ATP production from Acetyl CoA comes from the electron transfer chain, in which the final electron acceptor is oxygen.

So for any type of fat loss, I’d think that anaerobic work will be more energy inefficient (work efficient per fat loss), which is a good thing for our cutting purposes. Does anyone know if Acetyl-CoA will find itself in the ketone pathway in an anaerobic environment? (NewDAmage’s post suggests that to me, since no oxygen will block the use of the ETC and cause an Acetyl-CoA buildup) I was under the impression that ketone formation mostly occurred due to lack of CHO, in the long term, but can it also be a short term (rapid acting) pathway?

[/quote]

If I’m not mistaken, under anaerobic conditions glycolysis will be the main source of ATP; however at the end you’ll be converting pyruvate to lactate, which then must go to the liver to be converted back to pyruvate.

To my knowledge ketone bodies go on to be oxidized, in tissues other than the liver, to citric acid cycle intermediates.

I think this is where low-intensity cardio is favored by some during low carb dieting, as glycogen and consequently glucose supply is already low and in HIIT and the like, you’d be on the verge of excessive amino acid degradation for your energy needs.

[quote]ElbowStrike wrote:
So no wonder steady-state cardio doesn’t burn much fat. For every “calorie” of ATP burned in a lactic sprint, we burn 17 TIMES as much glycogen reserve as we would with the same amount of work done in a “steady-state” manner.[/quote]

This is kinda what T-Nation coaches have been saying for a long time. In losing fat, HIIT is better than steady state cardio. However, I’m not sure if this is the exact explanation why. I took up biochemistry over the summer, but we didn’t take up metabolism of fat.

[quote]NewDamage wrote:
To my knowledge ketone bodies go on to be oxidized, in tissues other than the liver, to citric acid cycle intermediates.
[/quote]

At least some of the ketones are excreted via sweat/urine/breath, I believe. Lots of potential energy going out of the body, there. Just something to think about. :slight_smile:

[quote]Lurker27 wrote:

At least some of the ketones are excreted via sweat/urine/breath, I believe. Lots of potential energy going out of the body, there. Just something to think about. :)[/quote]

Good point!

[quote]Lurker27 wrote:
NewDamage wrote:
At least some of the ketones are excreted via sweat/urine/breath, I believe. Lots of potential energy going out of the body, there. Just something to think about. :)[/quote]

These are ketones unusable by the body, like acetone, right?

It appears that way. Here is the wikipedia quotation:

Excess ketone bodies will slowly decarboxylate into acetone. That molecule is excreted in the breath and urine.

It should be noted that those were still burnable ketones at one point, and so the statement about energy loss stands.