How would a higher fat diet affect my body's response to exercise?

May 5, 2004
Outside Magazine
Dr. Phil Maffetone

February 7, 1996

koming question?
koming question 2?

How would a higher fat diet affect my body's response to exercise?

Dr. Maffetone, I'm wondering about the article in the February 1996 issue concerning the new 40-30-30 diet. As a triathlete, much of the article makes good sense. If fat requires more oxygen to process for energy, how would a higher fat diet affect the physiological responses to exercise? Thanks,
George Flatau

Annapolis, Maryland
[email protected]

George, Think of the fats in your diet as a source of energy for your aerobic system. As you develop that system through easy training, and as those dietary fats are taken in, certain advantages are conferred. Here's a quick list, based on the scientific literature:

1. Studies show that endurance capacity is increased in response to a "high" fat diet. 2. Researchers say that the capacity to use fats during prolonged training plays a more important role than previously thought. 3. Fats also play a significant role during high intensity, submax training and racing. 4. A low-fat diet (which is accompanied by a high carbohydrate diet) can inhibit the optimal refilling of the muscle's fat storage. This is significant because these fat stores in the muscle are responsible for much of its energy supply. 5. "High" fat diets prevent lower blood sugar levels following max exercise tests (and high carbohydrate diets produce lower blood sugar levels following max exercise tests). 6. Dietary fat restriction may neutralize some advantages conferred by training. 7. Studies show that a higher fat diet enhances resistance to fatigue and spares more glycogen.

We should be careful how we use the work "high" and "low" when referring to dietary fats; they are very relative terms, and researchers use them differently than most athletes. That's why percentages are good to use. The Surgeon General's Recommendations is 30%, with a unsaturated to saturated fat ratio of 2:1. The World Health Organization (WHO) recommends that athletes can safely consume a diet that's 35% fat.

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