Firefighting is a physically demanding occupation that may require 6,000 calories (kilocalories) per day. Firefighters who do not consume enough calories will become fatigued and lose body weight and muscle. Consuming too few calories over the weeks and months of a busy fire season can impair immune function and lead to illness. This is not the time to lose weight. Firefighters should check their weight every 2 weeks to monitor their energy balance. The best time to weigh is in the morning before breakfast (but after urination). Energy (calories) comes from carbohydrate, fat, and protein.

Fatigue, body and muscle weight loss can increase the potential for injuries and illness.  It is imperative that firefighters maintain a balance diet that is adequate to meet their dietary needs for a fitness regime and while conducting wildland fire operations. 

Eating for Health and Performance: The Wildland Firefighter