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

May 5, 2004
Outside Magazine
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Dr. Phil Maffetone

February 15, 1996

I'm always hungry. How can I stop feeling hungry?
I'd like to know more about this 40-30-30 diet
How does the 40-30-30 diet affect one's lipid profile?
Should food and fluid intake during competition be 40-30-30 as well?
How would a higher-fat diet affect my body's response to exercise?
How come I never feel like I'm getting enough food?

How would a higher-fat diet affect my body's response to exercise?
Question:Dr. Maffetone,

I'm wondering about the article in the February 1996 issue concerning the new 40-30-30 diet. As a triathlete, I think 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?

George Flatau
Annapolis, Maryland
[email protected]

Dr. Maffetone: 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, sub-max 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 word "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 recommendation is 30 percent, with an unsaturated to saturated fat ratio of 2:1. The World Health Organization says athletes can safely consume a diet that's 35 percent fat.

©2000, Mariah Media Inc.

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