Fat burning by ‘fasting’ during exercise

Much has been made of importance of carbohydrates immediately before and during exercise, particularly when it goes over 1 hour in length.  Our page http://www.irondaughterirondad.com/nutrition/carbs-protein-fat/ summarizes a few of the expert opinions on this.

A ‘new study’ seems to contradict that…I noticed a ‘Racing Weight Newswire’ on www.racingweight.com that says:

Exercise Fasting Increases Muscular Fat-Burning Capacity

Exercise fasting–or working out without consuming carbohydrate before or during the training session–has lately become a hot research topic and a popular practice among cyclists and triathletes. The results of a new study published in the Journal of Applied Physiology promises to increase the popularity of workout fasting even more.

Twenty non-athletes participated in the study, which required them to train on bikes 60 to 90 minutes at a time, four times per week. Half of the subjects performed the workouts with ample carbohydrate intake before and during, while the other half performed workouts in a fasted state. The overall diets of both groups were identical. The researchers found that fasted exercise increased the exercise intensity associated with the maximal rate of fat burning significantly more than normal training did: 21 percent versus 6 percent. However, changes in VO2max and 60-minute time trial performance were equal in the two groups.

This suggests that up to at least 90 minutes, not taking in carbohydrates prior to and during exercise may even have a fat burning benefit, without a drop in performance…something interesting to consider, particularly when trying to reduce calories…which I’m doing now.

Of course, contradictory to a lot of other advice…so go figure.  The human body is still largely a mystery even to the experts…and there are so many variables, that it’s very difficult to draw meaningful conclusions in general, and next to impossible therefore to determine what’s best for you.  In this study of course, it was non-athletes, not endurance athletes…it didn’t really deal with the impact on recovery and the impact of the idea on athlete’s that workout every day, or twice a day. 

The only minor good news is that the only body that you need to figure out is yours.  Coming up in a Post soon, another interesting new study reported in the New York Times that demonstrates the massive difference in how bodies respond to exercise…and how some just don’t.

Like all new ideas, it’s worth doing some further reading…most studies I read about are very limited, in small groups for short periods of time, and many times when repeated by someone else, deliver different results.  If I think that a new idea makes sense, I don’t jump on the bandwagon and ditch the old…but I may ‘nudge’ what I’m doing in the direction of a new idea to see if it’s valid for me.

I generally don’t drink anything but water on exercise up to an hour right now, when it’s cooler out, and I’m not sweating a lot.  Hotter though, I do add in a carb drink with sodium since I’m a ‘champion sweater’.  I may play with that a bit when things warm up.  In the meantime, I may just ‘always’ instead of ‘generally’ stay on water for the first hour or so, to see how I do.

Sometimes when my schedule in the morning gets stretched out a bit, I find myself 2-3 hours after my breakfast, with a time slot for a workout, and sort of between whether I should eat something or not before the workout…I may just specifically skip it, and see what happens…I often do now.

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