Protein deficiency may lead to symptoms such as muscle loss, thinning hair, brittle nails, skin inflammation, edema, slower recovery from wounds, easy starvation, higher risk of infections, and more emotional instability. Hair, skin and nails are composed of keratin, collagen and elastin, which are extremely related to protein, so when the body is deficient in protein, it will show up in these points. People who are deficient in protein have thinning hair that is fragile and prone to breakage. Lack of protein may also make the nails weaker and prone to break and run out of grooves. Also, lack of protein may predispose you to suffer from sarcopenia. As the body lacks sufficient protein intake, it turns to the muscles to extract protein to maintain other vital body functions. As a result, the muscles are gradually depleted, the amount of muscle mass decreases, and the person becomes weak. The recommended daily intake of protein is 1.1 grams per kilogram of body weight for adults and 1.2 grams per kilogram of body weight for the elderly. You can try to choose high quality proteins, such as milk, eggs, fish, chicken, beans, etc. to supplement your daily needs.