/sci/ - Science & Math » Thread #7617393

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Anonymous Mon 26 Oct 2015 16:17:31 No.7617393 View Reply Report Delete

Quoted By: >>7617430 >>7617448 >>7617471

Calories are measured via combustion in machines, right? But that does not mimic the human digestive system.

Are the calorie values for food actually the calories we are absorbing?

e.g. If I eat ten grams of pure fat am I really getting 90 calories?

If I drink ten grams of ethanol, am I really absorbing 70 calories?

Anonymous

Anonymous Mon 26 Oct 2015 16:29:40 No.7617430 Report Delete

Quoted By: >>7617449

>>7617393
Calories are a measure of energy generated from chemical reactions, whether it's combustion or cellular, the value is the same.

Anonymous

Anonymous Mon 26 Oct 2015 16:34:59 No.7617448 Report Delete

Quoted By:

>>7617393
Food calories are estimated from bioavailabity.

We know the metabolic pathways for certain classes of carbohydrates etc. Then you estimate from the energy changes from Hess' law using the composition of the food.

There are various cheap methods available to estiamte the composition.

Anonymous

Anonymous Mon 26 Oct 2015 16:35:12 No.7617449 Report Delete

Quoted By: >>7617455

>>7617430
In a pinch could I eat sawdust?

Anonymous

Anonymous Mon 26 Oct 2015 16:36:18 No.7617455 Report Delete

Quoted By: >>7617459

>>7617449
No, you don't have the bacteria necessary to digest sawdust in your gut like some insects and herbavoirs.

Anonymous

Anonymous Mon 26 Oct 2015 16:36:58 No.7617459 Report Delete

Quoted By: >>7617463 >>7617465

>>7617455
So the calorie measuring thing is wrong?

Anonymous

Anonymous Mon 26 Oct 2015 16:38:19 No.7617463 Report Delete

Quoted By:

>>7617459
Not him, but I'm guessing no, because there isn't the chemical reaction that insects and such experience

Anonymous

Anonymous Mon 26 Oct 2015 16:38:27 No.7617465 Report Delete

Quoted By:

>>7617459
No, your body just does not have the correct ingredients for the chemical reaction necessary to get at the chemical energy in the wood.

Anonymous

Anonymous Mon 26 Oct 2015 16:40:48 No.7617471 Report Delete

Quoted By:

>>7617393
No, you're actually getting 90,000 calories and 70,000 calories, respectively.

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