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This isn't so. Quoting [1], energy dissipated as side-effect heat during gestation and storage: Carbohydrates: 5 to 15% of the energy consumed Protein: 20 to

This isn't so. Quoting [1], energy dissipated as side-effect heat during gestation and storage: Carbohydrates: 5 to 15% of the energy consumed Protein: 20 to 35% Fats: at most 5 to 15% [1] https://en.wikipedia.org/wiki/Specific_dynamic_action https://en.wikipedia.org/wiki/Specific_dynamic_action

tezza 10y ago
This adds to my point, it does not subtract to my point. Not only is the fat digestion process inefficient, but on top the fat absorbtion process consumes more energy to make happen ( that heat ) We'd have to see where in the large 5-15% ranges various items stand. Sugar dissolving in water... I'd be amazed if that released 15% of the energy. I'm still amazed it would be as high as 5%, so thanks for that info EDIT: spatular set me straight with a detailed process for sugar absorbtion
- spatular 10y ago
  Well, fat digestion seems to be effective even comparing to hydrocarbons. I think longer hydrocarbons including sugar have to be broken into fructose and glucose during digestion. Fructose cannot be immidiately consumed by cells, so it's converted into glucose in liver. On top of that, there are about 5g of glucose total in bloodstream at any given moment, so exess have to be accumulated by liver/muscle cells that have to store it in a long-chain hydrocarbon form (glycogen). Each conversion requires some energy, so 5-15% isn't that much...
nomel 10y ago
> Protein: 20 to 35% Doesn't this assume that you're starving [1]? Proteins are a last resort, and since it's somewhat toxic to convert them, they're simply not processed if it can be avoided [2]. [1] https://en.wikipedia.org/wiki/Gluconeogenesis https://en.wikipedia.org/wiki/Gluconeogenesis "the process occurs during periods of fasting, starvation, low-carbohydrate diets, or intense exercise." [2] http://antranik.org/the-catabolism-of-fats-and-proteins-for-energy/ http://antranik.org/the-catabolism-of-fats-and-proteins-for-...
- spatular 10y ago
  Yes, looks like this. And in addition in average human this pathway is limited to 300g amino-acids -> glucose per day if I remember correctly. Still what should happen if protein intake is tripled say from 50g/day to 150g/day? Excess amino acids have to go somewhere...

tezza 10y ago

This adds to my point, it does not subtract to my point. Not only is the fat digestion process inefficient, but on top the fat absorbtion process consumes more energy to make happen ( that heat ) We'd have to see where in the large 5-15% ranges various items stand. Sugar dissolving in water... I'd be amazed if that released 15% of the energy. I'm still amazed it would be as high as 5%, so thanks for that info EDIT: spatular set me straight with a detailed process for sugar absorbtion

spatular 10y ago
Well, fat digestion seems to be effective even comparing to hydrocarbons. I think longer hydrocarbons including sugar have to be broken into fructose and glucose during digestion. Fructose cannot be immidiately consumed by cells, so it's converted into glucose in liver. On top of that, there are about 5g of glucose total in bloodstream at any given moment, so exess have to be accumulated by liver/muscle cells that have to store it in a long-chain hydrocarbon form (glycogen). Each conversion requires some energy, so 5-15% isn't that much...

nomel 10y ago

> Protein: 20 to 35% Doesn't this assume that you're starving [1]? Proteins are a last resort, and since it's somewhat toxic to convert them, they're simply not processed if it can be avoided [2]. [1] https://en.wikipedia.org/wiki/Gluconeogenesis https://en.wikipedia.org/wiki/Gluconeogenesis "the process occurs during periods of fasting, starvation, low-carbohydrate diets, or intense exercise." [2] http://antranik.org/the-catabolism-of-fats-and-proteins-for-energy/ http://antranik.org/the-catabolism-of-fats-and-proteins-for-...

spatular 10y ago
Yes, looks like this. And in addition in average human this pathway is limited to 300g amino-acids -> glucose per day if I remember correctly. Still what should happen if protein intake is tripled say from 50g/day to 150g/day? Excess amino acids have to go somewhere...