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How does the heat index affect your nutrition?


Athletes can and do perform effectively in hot weather, but they can falter when they don't give enough respect to the dangers of heat.
Athletes can and do perform effectively in hot weather, but they can falter when they don't give enough respect to the dangers of heat.
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You've probably made a similar evaluation during oppressively warm weather: "It's not so much the heat, but the humidity." The statement, while almost a cliché, recognizes that the temperature reading on a thermostat isn't the only measure of how you feel when Mother Nature bears down. The heat index is a more scientific and precise accounting of the forces that create discomfort or, alternatively, conditions that feel pleasant to the human body.

The heat index uses 25 percent humidity as a baseline. If, for example, it's 100 degrees Fahrenheit (37.78 degrees Celsius) outside and humidity is at 100 percent, you're experiencing the equivalent of a 195 degree day (or 90.56 degrees Celsius) at 25 percent humidity. That's a statistic that gets people's attention and helps them appreciate the dangers of exertion in such an environment -- which is the intent of the heat index.

Hot weather forces your body to work harder and burn more calories [sources: Mirkin; Popke]. Your heart is increasingly called upon to distribute overheated blood to the skin for cooling, the liver and kidneys are taxed to a greater degree, and vital water -- even your muscles are made of more than 70 percent water -- is lost through sweating at a much faster rate [sources: Ryan; Mirkin; Popke].

All of these factors can lead to everything from cramping and nausea to the shutdown of organs, heatstroke and even death [sources: Popke; Weill Cornell Medical College]. Undertrained athletes and the elderly are at particular risk, but the threat of sickness and death is very real, even for fit, elite and professional athletes [sources: Popke; Weill Cornell Medical College].

Click ahead to learn how you can alter your nutrition for optimum health and safe performance in less-than-ideal conditions.


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