Thermic effect of different macros

[lookingforgains]

I have always heard that when protein is eaten about 20% worth of its calories are used during digestion.
This would mean if one ate 100 cals worth of protein, than they would end up with only 80 net calories. Carbs have been said to burn about 10% worth during digestion and fats around 3%.
This would mean that even on iso caloric diets a high-protein diet would yeil less calories than a high fat or carb diet.

Can anyone confirm to what extent any of this is true?

[beaul]

yes its true. Protein can be upwards of 30%. I tried to find some studies real quick, but couldn't find any free ones.

[beaucephus]

Yes true. Not only the thermic effects, but you have to take into account the hormonal effect of the macros you're ingesting as well.

I think Carbs are 6% vs. ~25% for protein and 3-4% for fats.

[mfbarbmff]

"The magnitude of the thermic effect can vary from 3% to 30%. Protein foods elicit
a thermic effect of up to 30% of the meal's total calories. Natural starchy and fibrous carbohydrates are a close second at around 20%. Fats and refined carbohydrates have a very low thermic effect (fats only elicit a 3% thermic effect). This is one of the reasons dietary fat is so easily stored as body fat. The fact that dietary fats have only a 3% thermic effect)

Quoted directly from Tom Venuto's book Burn the Fat, Feed the Muscle

[Emma-Leigh]

I wrote a bit about it here:
http://forum.bodybuilding.com/showthread.php?t=113945491

Also - check out my LINKS post: http://forum.bodybuilding.com/showthread.php?t=110624041
^
it has it outlined in http://www.fao.org/docrep/006/y5022e/y5022e04.htm < that link.

[Dr Clay]

This is very true and is precisely why I came up with the term "available energy." This refers to the amount of energy that will be available from a food once it is broken down.