For the skinny on fat utilization compared to carbs read these....


http://www.bodybuilding.com/fun/randy10.htm

http://dl.clackamas.edu/ch106-07/carbohyd1.htm

http://www.weightawareness.com/topics/doc.xml?doc_id=1344&_topic_id=1460

http://www.indoorclimbing.com/foodfat.html

http://muscle.ucsd.edu/musintro/fattyacid.shtml

http://instruct1.cit.cornell.edu/courses/ns421/Fats.html

http://www.ajcn.org/cgi/content/abstract/67/3/5355

I don't know about that first link... guy has some issues with math (apparently he thinks there are a different number of grams in a pound of protein than there are in a pound of carbohydrates :) )

He also has no data to support his initial conclusion about muscle loss while not eating fat. In fact, he states that he dropped about 30% of his daily caloric intake, while increasing the number of calories burned (due to circuit training). I fail to see how a loss of lean muscle mass is surprising, given what he did...

why does link 3 contradict with link 4 regarding fat as highest source of energy?

I don't know about that first link... guy has some issues with math (apparently he thinks there are a different number of grams in a pound of protein than there are in a pound of carbohydrates :) )

* THE 9-4-4 NUMBERS that nutrition-savvy consumers can recite with the fluency of the alphabet are approximations (http://findarticles.com/p/articles/mi_m0820/is_n230/ai_18696320) meant for rough calculations. For example, the notion that carbohydrates have four calories per gram is rounded up from 3.6. Protein tends to have 4.1 or 4.2 calories per gram, depending on the source (http://findarticles.com/p/articles/mi_m0820/is_n230/ai_18696320).

Kross...once you get past the preferential "bias" of the writers , they both make the same observations to an extent regarding the speed at which fats can be mobilized for energy and the order in which fuels are "burned" depending on the aerobic or anaerobic activity.

Even though one states that fats are our most "precious' energy source, the same article later rails against excessive consumption.

But...that's the net...more "absolute truths" out there than you can shake a stick at..:cool:

Kross...once you get past the preferential "bias" of the writers , they both make the same observations to an extent regarding the speed at which fats can be mobilized for energy and the order in which fuels are "burned" depending on the aerobic or anaerobic activity.

Even though one states that fats are our most "precious' energy source, the same article later rails against excessive consumption.

But...that's the net...more "absolute truths" out there than you can shake a stick at..:cool:


ah okay thnx. so do you believe that fat is our highest source of energy?

I believe it is ATP.

:D

I don't think the body is too particular where it gets its energy from. What I would surmise is that it takes the energy from the source that requires the least energy to obtain, working from easiet to get to hardest to get.

From what I understand about blood sugar (glucose), it is the primary source of energy for the cells. So by definition, since glucose is technically a carbohydrate, then the body "prefers" carbohydrates.

To a large degree though, if you want to efficiently 'burn' fat you need carbs. Pyruvate is necessary to keep the other components of the Krebs cycle (http://en.wikipedia.org/wiki/Citric_acid_cycle) moving. Pyruvate is basically half a glucose molecule so if it's not avaliable (through food or glycogen via glycolysis (http://en.wikipedia.org/wiki/Glycolysis) ), it needs to be made avaliable and uses glycerol as a component via B-Oxidation (http://en.wikipedia.org/wiki/Fatty_acid_metabolism) (lipolysis). However fats are inefficient at giving up pyruvate so protein can be converted (gluconeogenesis (http://en.wikipedia.org/wiki/Gluconeogenesis)) in the liver and kidneys


Not an overly technical answer but good enough. I may be off on some points, feel free to correct where necessary.

cheers