Fasting refers to abstaining from food and drink for a period of time. It is an ancient practice followed in many religions. Fasting has many health benefits including detoxification, immune system boosting, disease prevention, and longevity. There are different types of fasts based on duration, purpose, and foods/drinks allowed. Fasting improves health by allowing the body to eliminate toxins and waste at an increased rate. Potential signs of detoxification during a fast include gas, bad breath, and coated tongue. Fasting has physiological effects like increased insulin sensitivity and reduced oxidative stress.