"As with most endurance-based athletes, triathletes commonly strive to achieve a low body fat level in order to improve their power-to-weight ratio. This fascination with weight loss amongst triathletes has led to the popularity of so-called high-protein, low-carbohydrate diets. These diets are low energy (kilojoule) diets and decrease body weight not because of the combination of nutrients but because they are low in energy. Athletes following such diets to lose weight run the risk of failing to recover adequately from training."
"As with most endurance-based athletes, triathletes commonly strive to achieve a low body fat level in order to improve their power-to-weight ratio. This fascination with weight loss amongst triathletes has led to the popularity of so-called high-protein, low-carbohydrate diets. These diets are low energy (kilojoule) diets and decrease body weight not because of the combination of nutrients but because they are low in energy. Athletes following such diets to lose weight run the risk of failing to recover adequately from training."
http://www.ausport.gov.au/ais/nutrition/factsheets/sports/triathlon