Protein deficiency can result in a malfunctioning metabolism, a weak or irregular immune system, and - possible blindness and deafness - a rapid period of weight loss - a significant and rapid weight gain - damage to connective tissue and bones

ANSWER:

Protein deficiency may lead damage to connective tissues and bones.

EXPLANATION:

The lack of proteins may reduce muscle mass and therefore a person may lose significant weight in less time. The lack of proteins may also lead one to eat more because proteins keep one satiated for longer time periods. Low protein intake increases appetite and so a person may gain weight. Proteins are important to build string tissues and muscles and a deficiency of proteins may lead to damage of the connective tissues and muscles.