No matter what type of "heat protectant" you apply to your hair before curling or flat ironing it, if you use excessive heat on your hair, your hair will begin to get dry and eventually break off. The best way to protect the hair from excessive heat is to create different hairstyles within the hair or try a different approach to maintaining the heat style without using heat.
How to maintain a heat style without using heat:
Wrap the hair at night and prior to showering and/or bathing.
Pin curl, flexi rod, or roller set the hair at night to help maintain the curls.
Alternative hairstyle options to avoid heat: