T Nation

Carb and fat burning ratio


okay man so i got this guy who beleives that calories from carbs burns faster than calories from fat

this sounds absolutely ridiculous to me

anyone else think this?

anyone have any good reads on the topic?


Well, it's true I suppose, but only in a pretty trivial sense: the thermic effect of the processing of dietary fats is about 2%, while the thermic effect of carbs is roughly 10%. If you think about it, I suppose that would mean that over any given period, consuming carbs would burn off faster than fat. So, it's right, but it's also pretty trivial.


if its right then how is it trivial?


It's trivial because you're talking about the thermic effect of your body processing the nutrients. You're talking about an 8% differential when most people's problem tends to be more related to balance, taking in the right amount of nutrients to be healthy, exercise, etc.

It's also trivial because anyone concerned about that differential who will actually see results from its manipulation will often be guided not by those thermic effects, but instead by the way his or her body reacts to ingesting different P/C/F ratios as it relates to performance.

I mostly say that you shouldn't worry too much about that thermic effect, though, because it shouldn't be used as a reason to take in more carbs than fats in a way that's different from ratios that you normally hear. Also note that carbs have lower levels of satiety etc--in other words, there are many countervailing forces acting around the thermic effect that influence decision-making regarding nutrient profiles.


i think he is reffering to how fast the body burns carbs vs fat(like the actual speed)...not how much energy is requried to burn either carbs or fat which is TEF...


I think calories burning "faster" is maybe a bad way to describe metabolism? there are other differences though


Isn't it easier for our bodies to derive energy (ATP) for muscle contraction from glycogen as opposed to fat? Think that's what he means?


Carbs = 4kcals/gram, Fats = 9kcals/gram, this is why your body prefers carbs for energy. Your body is able to go through more grams of carbs then it can fat in any given time. Your friend is correct.