Final answer:
Blow-drying hair excessively may cause dryness and brittleness, which can lead to hair loss due to damage to the hair cuticle and disulfide bonds.
Step-by-step explanation:
Excessive blow-drying may result in the loss of hair. When the hair is exposed to high heat from a blow dryer, it can cause the hair to become dry and brittle, which leads to breakage and potential hair loss. This is due to the disruption and potential damage to the hair's cuticle, which is the protective outer layer of the hair strand. Furthermore, excessive heat can lead to the degradation of disulfide bonds within the hair's structure, which are responsible for its strength and elasticity. Therefore, it is important to use a heat protectant product when blow-drying hair and to avoid excessive heat settings.