The Energy Balance Equation

[lylemcd]

I don't mind getting the grammar/spelling corrections, I often type quickly and don't check as closely as I should and would rather it be correct than not.

[soultransfer]

out of your article...

I’d also note that people often make comments about the above equation which shows just how utterly clueless they are about it. For example, people will point out that replacing carbs with protein leads to greater weight loss although they have the same calories; ergo the equation is wrong. What they fail to realize is that protein has a higher thermogenic effect and this modifies the TEF value of the equation; the energy OUT side of the equation changes if you replace carbs with protein. But they seem to try to treat the sides of the equation independently in this case; which is wrong.

i do not get that completely.
Energy In (corrected for digestion) = (BMR/RMR + TEF + TEA + SPA/NEAT) + Change in Body Stores

if you replace carbs with protein (same amount of calories), the left side of the equation stays the same or changes slightly due to disgestion issues.

TEF goes up. Changes in Body Stores has to decrease (tissue loss) so the equation reamains balanced?
correct?

[lylemcd]

Yes.

[mjs]

Lyle,

Just came across your article on the Energy Balance Equation.

In the article you state

The equation is perfectly valid and humans are as subject to the laws of thermodynamics as anything else in the universe. Physics is not just a good idea, kids, it’s the law.

As a physicist I can tell you this is not exactly correct. I assume that when you mention the laws of thermodynamics you are talking about the first law of thermodynamics that is often stated as such

For all adiabatic processes between two specified states of a closed system, the net work done is the same regardless of the nature of the closed system and the details of the process.

This important part in regards to your article is "of a closed system". Since the human body is not a closed system, the first law of thermodynamics cannot be applied in this way.

You can apply the first law of thermodynamics to non closed systems but things start to get messy with something as complex as the human body and it really screws up your equation.

[lylemcd]

Why is the human body not a closed system?

[mjs]

Originally Posted by lylemcd

Why is the human body not a closed system?

Most basically because there is heat transfer. Also we do things like poop, breath, and sweat.

[tominho7]

the human body is an open system, and the first law of thermodynamics still applies.

"The First Law states that energy cannot be created or destroyed; rather, the amount of energy lost in a steady state process cannot be greater than the amount of energy gained"

Extra calories will always end up somewhere. it does not matter if you believe this is true or false, it will still be reality.

[dmoney19]

Originally Posted by mjs

Most basically because there is heat transfer. Also we do things like poop, breath, and sweat.

Would these not be covered under BMR? The pooping was talked about in the article as well....