Tuesday, February 28, 2012

High-fat versus low fat diets for endurance training and exercise performance

 Assignment for class:

I found the section in our book labeled "High-fat versus low fat diets for endurance training and exercise performance" interesting.  Supporters of the high-fat diet for endurance athletes say that an increase in fat intake overtime will encourage the burning of lipids by increasing the capacity mobilize and breakdown fat (1).  In a study done on two groups of males who had the same fitness status, one group was fed a high-carbohydrate diet (65% calories from carbs), and the other group was fed a high-fat diet (62% of total calories from fat).  Both groups exercised 3 days a week at 50-85% of their VO2max (aerobic capacity), for 60-70 minutes during the first 3 weeks, and 4 days a week during the last few weeks.  What the study found was that there was an increase in endurance capacity for those who consumed the high-fat diet (115%), however, the high-carbohydrate group was able to increase their endurance substantially (194%) (1).

Also, our book states that, "Comprised training capacity and symptoms of lethargy, increased fatigue, and higher ratings of perceived exertion usually accompany exercise when subsisting on a high-fat diet" (1).  It is important to remember that there negative health hazards associated with a high-fat diet.  What I found interesting, though, was that this risk may not be a hazard for athletes who burn a ton of calories each day (like endurance athletes), and consume a higher-fat diet (around 50% calories from fat, not the 62% like in the study).  This will NOT increase the risk for heart disease or elevated cholesterol levels, if the athlete maintains a healthy or stable body weight and is able to burn many calories each day (1).

Also, our book states that, "Conversely, significant restriction of dietary fat intake below recommended levels also impairs endurance performance" (1).  So, I think it's very important that athletes recognize this, especially if they are burning a lot of calories each day through training.  They NEED fat, and cannot limit it to dangerously low levels because they will NOT be able to give 100% in each workout or race.  They are still going to have great numbers for blood lipid profiles, triglycerides, etc., as long as they're burning enough calories each day.  I think it's out job to help people understand this.  There is so much junk out there in the media!
1.  McArdle, W. D., Katch, F. I., & Katch, V. L.  (2009).  Sports and exercise nutrition.  (3rd ed.).
            Batimore, MD:  Lippincott Williams & Wilkins. 

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