4 ms·

Thermodynamics have nothing to do with it. Human bodies can vary when it comes to efficiency of converting food to energy. It may also depend on hormonal situat

Thermodynamics have nothing to do with it. Human bodies can vary when it comes to efficiency of converting food to energy. It may also depend on hormonal situation or genetics or w/e else. It may also well be that "calorie out" part depends to some extent of what is eaten. It's not like human bodies are perfect 100% efficient engines of converting food to energy and that rest of the body doesn't take into account what's "in the tank" at any given moment. Thermodynamics argument just doesn't mean anything. It's probably the most silly way to end sensible discussion on this topis.

nkozyra 12y ago
Actually, thermodynamics and the conservation of energy is absolutely a factor - the questions you're bringing up have to do with the way we measure that energy usage and potential, not with the fact that energy is either used (stored) or expelled. The efficacy of metabolism is in my opinion very much the big question mark here, and why I think relying on one-size-fits-all concepts like "a carbohydrate translates to 4 kilocalories" is simplistic and in all likelihood flawed.
- iopq 12y ago
  No, actually carbohydrates are extremely easily digested and used as energy directly by your muscles and other tissues. Fats are also easily digested and used as energy primarily when you sleep. It's protein that's hard to quantify (how much is converted to glucose? how much does it cost to generate 1 gram of tissue? how many calories does it take to digest?)
  - nkozyra 12y ago
    I'm confused, where did I say carbohydrates are not easily digested?
spudlyo 12y ago
Human bodies can vary when it comes to efficiency of converting food to energy. I do not doubt this, but is there any evidence that these variances are significant? Treating human bodies as 100% efficient food to energy converters is useful for practical reasoning about weight loss; unless these factors are significant, focusing on macronutrients, genetics, or the "hormonal situation" is just getting lost in the weeds.

nkozyra 12y ago

Actually, thermodynamics and the conservation of energy is absolutely a factor - the questions you're bringing up have to do with the way we measure that energy usage and potential, not with the fact that energy is either used (stored) or expelled. The efficacy of metabolism is in my opinion very much the big question mark here, and why I think relying on one-size-fits-all concepts like "a carbohydrate translates to 4 kilocalories" is simplistic and in all likelihood flawed.

iopq 12y ago
No, actually carbohydrates are extremely easily digested and used as energy directly by your muscles and other tissues. Fats are also easily digested and used as energy primarily when you sleep. It's protein that's hard to quantify (how much is converted to glucose? how much does it cost to generate 1 gram of tissue? how many calories does it take to digest?)
- nkozyra 12y ago
  I'm confused, where did I say carbohydrates are not easily digested?

spudlyo 12y ago

Human bodies can vary when it comes to efficiency of converting food to energy. I do not doubt this, but is there any evidence that these variances are significant? Treating human bodies as 100% efficient food to energy converters is useful for practical reasoning about weight loss; unless these factors are significant, focusing on macronutrients, genetics, or the "hormonal situation" is just getting lost in the weeds.