Art De Vany: Fat Mobilization and Antioxidants

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Fat Mobilization and Antioxidants

October 24, 2005 12:22 PM

Fats are readily oxidized and contain about twice the energy as carbohydrate or protein (9 calories versus 4 calories per gram). You carry far more metabolizable energy as fat than any other fuel. So, why do runners, bikers, hikers, and, well you name it, consume so much carbohydrate? They have their reasons, but I am not so sure they are that sound.

Consuming high carb diets makes one a very poor mobilizer of fat. This is one path through which high carb diets, in excess of energy expenditure, contribute to the accumulation of fat through a decrease in the rate of fat utilization. So, an endurance athlete who is not good at mobilizing fat as energy is in more danger of depleting muscle glycogen. It is also true that carbs are a potent source of free radicals that cause fatigue and tissue inflammation.

Now, it turns out that women are gaining on men in the ultra marathons that are run over several days in Death Valley (fitting in my mind). One reason given is that they are better mobilizers of fat than men. Using fat as an energy lowers their oxidative load and they do not tire so readily. Women probably eat more antioxidant-rich foods than men, though that is not reported.

Another factor is that being low on antioxidants seems to make one a poor mobilizer of fats as a source of energy. A study in Lipids, 2005; 40(4):433-5 suggests that athletes on a low antioxidant diet (low in vitamin C and beta-carotene) had lower circulating levels of omega-3 and omega-6 fatty acids compared to athletes on the same diet but high in antioxidants.

From an evolutionary perspective, fat was the prefered endurance fuel. The sorts of carbohydrate-laden foods and drinks modern athletes consume did not exist; in fact, there were no simple carbs 100,000 years ago. Our ancestors ate wild plants that were very high in antioxidants and consumed as much fat as they could, meaning that the lean animals they ate had to be processed to capture all their fat content.

With this perspective...

the effect of high antioxidant content on fat mobilization in the research cited makes sense.

That leaves a curious mismatch between the modern practice of endurance athletes and the evolutionary record. There may also be a physiological mismatch of modern endurance activities with ancestral endurance patterns. The latter may have been more intermittent, with a burst-rest pattern giving ample time to replentish muscle glycogen.

Sherpas who climb the Himalyas and Tarahumara Indians who run great distances have endurance that is legendary and well-documented. They both are kind of chubby. Endurance athletes look gaunt or emaciated by comparison.
I bet Sherpas and Tarahumara Indians are great mobilizers of fat.

There seems to be is a missing piece of the modern puzzle of how endurance athletes have become so dependent on carbohydrate as a fuel. I would suggest the research has some voids or bias and that sponsorship and commercial interests may contribute to that.

· Evolutionary Fitness

Comments

Posted by: Flower Online at September 12, 2006 2:18 AM

Godot - I was waiting for you to post.....

Posted by: Chris H at July 31, 2006 4:01 AM

I think you are mistaken about any significance in women gaining on men in Death Valley (if that's even the case). If you are not familiar with the Badwater race and its pool of entrants you could be forgiven for trying to make a statistical analysis of the finishing times. The race is unique, the small pool of entrants is not uniform over time with regard to motivation, talent, training and performance. And among ultrarunners, there are well-known outlyers: for instance, Ann Trason, whose performances often rivaled top male competitors and were HOURS ahead of her female competitors. Not being a physiologist or biologist, I cannot properly weigh your arguments about carbohydrate being poor fuel for athletes. Historically, though, it doesn't seem to have negatively affected the times of endurance runners. In other words, can you point to a drop-off in performances after carbo-loading became popular, or after the introduction of energy gels? If you are inclined to make a case based on the Badwater race, I would think you might be able find performance statistics in a much larger context to support your thesis.

Posted by: godot at March 28, 2006 2:18 PM

Pruzicka,

Earlier this year a meta-analysis was published comparing high-carb versus high-fat diets on endurance performance (Int J Sport Nutr Exerc Metab. 2005 Feb;15(1):1-14). The conclusion was that there is not enough evidence to support a high-carb diet over a high-fat diet. Apparently, the studies involved were too dissimilar to make any generalizations. I would bet that more studies on this subject are currently underway.

Posted by: Matt M at October 25, 2005 10:07 AM

Are there know endurance athletes with results that do not consume lots of carbs, ie. take their energy from fat ?

Posted by: pruzicka at October 25, 2005 7:20 AM

Chris Hola...from what i know, which of course might be wrong, we seem to have not adapted to eating grains sans experiencing the deleterious effects;thats the point
Sure some folks have a blunted insulin response and could perhaps be thus described and 'metabolically advantaged' as they trough away the spag bog with extra garlic bread and not look like Mama Cass the next morn but nevertheless one canny escape the effects of bludgeoning ones insulin receptors in the long run.
Anyways just throwing it into the (bread)mix !
Simon

Posted by: simonfellows at October 24, 2005 9:36 PM

I wonder if - given the prevalence of warring agricultural societies in certain parts of the world - the genes for adaption to eating grain etc. didn't perhaps spread a little faster than a simple comparison of timescales might suggest. I suspect a boom caused by a few good harvests is rather larger in real terms than the natural variation of numbers of predators/prey.

This doesn't invalidate the underlying point, endurance atheletes probably still eat suboptimally - but it might point to a explanation.

Posted by: Chris Stiles at October 24, 2005 6:24 PM

Fat Mobilization and Antioxidants

October 24, 2005 12:22 PM

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