Final answer:
Dietary fiber or cellulose is the type of complex carbohydrate that does not supply energy or heat to the body, but is essential for maintaining digestive tract health.
Step-by-step explanation:
A type of complex carbohydrate that does not supply energy or heat to the body is known as dietary fiber or, more specifically, cellulose. Unlike other carbohydrates such as sugars and starches, which are broken down into glucose to provide 4 Calories of energy per gram, dietary fiber is largely indigestible by the human digestive system. Although it doesn't contribute calorific energy, fiber plays a crucial role in digestive health, aiding in the maintenance of the gastrointestinal tract and helping to keep things moving efficiently within the digestive system.