Your Body Lies

Athletes are often told, "Listen to your body." While that strategy is good in many circumstances, it doesn't always work--because your body lies. Okay, maybe it doesn't "lie," but your body can give you faulty information that may cause you problems if you listen.

Some of the best environments for faulty signals saying "I'm not hungry" or "I'm not thirsty" include:

  • Hot temperatures
  • Humid conditions
  • Stressful situations (racing)
  • Altitude

This has been one of the hottest summers on record. The heat, and in some cases humidity, causes athletes to lose their appetite. In addition to appetite suppression, it is difficult to keep hydrated in the heat.

While you do not have to keep perfectly balanced (body weight the same before a long workout and after a long workout,) it is important to keep the losses minimal. If athletes do not eat or drink enough during a single day, performance can be affected for the following few days. If athletes do not consume enough fluid and fuel day after day, this is a slow progression to failure. Carbohydrate depletion, a "bonk," can occur and this can lead to poor training or terrible race performance.

In the past month athletes have commented to me that a race started out well, but as the race went on, it felt like all the energy was drained from their legs. When we talk about what they've eaten in the days leading up to the race, race morning and during the race, I often find they are not eating enough. Not eating enough during a race is particularly easy because of distractions such as other participants, weather, the course, race tactics and bicycle handling. Racers can get distracted and not pay attention to fluid and energy needs.

Participating in a race at higher altitudes can also affect appetite and thirst signals. The body actually burns more calories and uses more fluid at altitude, but altitude also decreases the body's desire to eat and drink. Add hot temperatures and racing to the altitude mix and athletes get a triple whammy.

If you are experiencing "the fade" in your current training or a recent race, the first step is evaluation. Write down everything you eat and drink for a few days. If possible, evaluate at least one race day as well.

To help you make a personal evaluation, some reference formulas are in this column. The formulas are ballpark values and may have to be slightly adjusted to fit your metabolism and exercise economy:

To sustain being a regular person, each day, you need approximately 30 calories per kilogram of body weight. To find your weight in kilograms, take weight in pounds and divide by 2.2. For example, if weight is 140 pounds, weight in kilograms is 140/2.2 = 63.6 or 64 kg. To find daily caloric needs, take 64 x 30 = 1920 calories. At 140 pounds, it takes roughly 80 calories per hour (1920 calories/24 hours) to fuel your body. Of course the exact value changes depending if you are awake and active or sleeping, but 80 calories per hour is a good start.

Modify this base formula as appropriate:

  • Add more calories (about 100 to 300) to the daily total if you lead an active lifestyle. Subtract calories if your lifestyle is low-activity.

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