Healthline shares a number of factors that can cause a person to be more susceptible to illness, including an unbalanced diet, dehydration, sleep deprivation, dirty hands and poor oral health. Failing to maintain a healthy lifestyle can therefore result in becoming sick more quickly.
According to Healthline, without a well-balanced diet, a body is not able to work at its peak performance thus making it more susceptible to illness. The body depends on water for all functions. Without the proper amount of water, nutrients and minerals are not carried throughout the body, reducing its ability to fight illness. During sleep the immune system releases cytokines, which are proteins that help fight against inflammation and disease. Without the proper amount of sleep the body does not replenish the needed proteins, making the immune system weaker.