Body Fat & Runners

Body composition is important and does affect performance. Let’s first get a caveat out of the way. This topic is a slippery slope! Less may be good to a degree and then it is exceedingly NOT good and in fact life threatening.

The recommended ranges of body fat for the general population are 15-18% for males and 25-30% for females. Of course, as you have certainly read, the general population far exceeds these ranges. So, if you are in that group of the general population and you run, work on getting into the normal range and your times may indeed improve. Most competitive runners are routinely below those levels. Elite male runners are in the single digits – 5-8%. and elite female runners hang in the 10-15% range. Yes, some are below these ranges. These figures come from research on Olympic level runners in the early 90s.

I won’t review all the physiology of fat here. However, fat is essential to life and is critical in the manufacturing of hormones in our bodies. It is why women whose body fat is reduced to those single digit levels often do not menstruate and there are other health risk elements that arise as well (i.e. bone loss later in life).

Most body fat is not readily accessible for energy use. It also is slow to break down into energy compared with carbohydrates. This is why we rely so heavily on carbohydrates as athletes. Excess body fat is certainly not desirable. It would be like wearing a weight vest while running. This is why when someone is on a weight loss program that they invariably get faster as they shed pounds of fat.

Let’s figure you are 165 pounds (75 kg) and have 20% body fat. That is 33 pounds of fat. At 10% you have 16.5 pounds of fat on you. Now, here is an interesting calculation for you. It takes ABOUT one calorie per one kilogram of body weight to move you one kilometer. A marathon is 42.2 kilometers. At 75 kg of body weight it would take 3165 calories (75 x 42.2). There are 9 calories per gram of fat. 3165/9= 352 grams of fat. In fact, research shows that not more than the equivalent of only 200 grams of fat are needed for energy during a marathon for instance. That is about 7 ounces!

By the way, let’s dispel a myth while we’re at it. The pace at which you run does not affect body composition. Though you burn slightly more fat at modest paces, it has been shown not to affect body composition. The modest-pace-fat-burning running advocates are misusing data to earn a buck. They sell “fat burning” workouts to everyone because it sounds so good.

What has been shown effective in losing fat is consistent training and higher speeds of running. Why? You burn more calories per unit of exercise time and increase your basic metabolism post-workout, burning even more! In the end expending more calories – which is the only way to reduce body fat – create a deficit in the calorie intake-output process.

The bottom-line is that though lowering your body fat levels may help you run better it is not a guarantee. If you are over the recommended levels for “average” males or females, it might be healthy to lose some of that fat through a solid exercise program – including weight or resistance training to build muscle. However, running faster, doing the right workouts, and consistency in training are far better predictors of your running success than body fat measurements.

And as a final note, remember we can only be the best “us” we can be. Our body metabolisms and chemistries are unique. So, be careful about jumping to conclusions looking at the person who just finished in front of you with a couple less pounds (or more for that matter!).


About Dean Hebert

I’m a mental game coach, author and speaker. I work with individual athletes, parents, coaches, and teams on sports performance enhancement. Beyond my academic post-graduate work in sports psychology - the psychology behind athlete performance – I am a certified Mental Games Coaching Professional (MGCP) and certified hypnotherapist. I’ve authored several books and hundreds of articles. “Coach, I didn’t run because…” (2008) is a seriously light-hearted look at making excuses not to workout and how to overcome them. “Focus for Fitness” (2009) and “Screw the Goals Give me the Donut” (2010) are two of my eBooks on mental game approaches for the everyday athlete. I wrote these because I believe that everyone can benefit from the powerful mental techniques that the world’s best athletes use. I have been cited in Runners World, Best Health magazine (CN), SWEAT Magazine, and the Washington Examiner amongst many other publications. I have been a featured mental games coach in Runner’s World and for the internationally acclaimed trail running resource - I also regularly appear on sports and fitness talk shows such as LTKFitness, Runnersroundtable and for more than three years I have co-hosted a weekly video series with Coach Joe English for I specialize in mental toughness training. My clients include tennis, synchronized swimming, golf, race-kart, soccer, motocross, volleyball, MMA, cycling (road, off-road, time-trialist), running, duathlon and triathlon, basketball, football and baseball athletes. I have coached world-class athletes and athletes internationally. I have a passion for working with youth athletes and helping them apply mental game skills and techniques to all areas of life. Most importantly, my aim is to have people enjoy sports and life to their fullest through peak performances.
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11 Responses to Body Fat & Runners

  1. Vito says:

    Very honest, truthful, and intelligent article. The exercise industry is infested with cockroaches. It is all designed to appeal to your ignorance. The government allows their lies to separate you from your money and leaving you bitterly disappointed. They are scum.

  2. Tom says:

    Wonderful article. Consise, factual, and very much to the point. Their are so many myths, scams, and mis-used information written about fitness today. This is a nice change of pace.

  3. Fern says:

    I really appreciate this article. I’m realizing now that my body fat is just about perfect for racing. I had been under the impression previously that I should get down to 8% to be really good, but I now realize that it might be too low and even unhealthy for a female to reach that level. Thank you!

  4. James Mason says:

    How about if your body fat is very low? around 2.6% for a male. Would this negatively affect performance?

    • Dean Hebert says:

      Interesting question. There is most certainly a low % at which it is bad for your health. Many hormones and other biochemicals and processes rely on fat. I cannot definitively say it is good or bad. But there most certainly are overall bad aspects to being that low.

  5. MK says:

    I am an avid runner with mediocre times. My body fat percentage is around 24%-25% but I am technically underweight (BMI of around 17). What can I do to better my times/lower my percent body fat?

    • Dean Hebert says:

      First, all the measures and charts for “normal” are guides and so don’t take them as gospel. Body morphology has a lot to do with it. If you have a muscular build for instance the numbers do not tend to be as accurate.Unless you had your body fat done by hydrostatic weighing take it with a grain of salt as to accuracy. That being said there is absolutely no secret to proper weight management for athletes. Dump junk food, desserts and alcohol. Don’t eat within 2 hours of bed time (nothing with calories, nada other than water). Have breakfast. Eat most of your calories by midday NOT evening meal. Don’t skip meals. For “ball park” purposes, be sure you have about 60% of your calories in carbohydrates. Take in some of your daily calories within the 30 minutes after a workout.

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