This document discusses the effects of sugar on the human body. It notes that sugar is a sweet crystalline substance consisting mainly of sucrose and is used as a source of energy, income, and preservation. However, sugar is highly addictive as it releases rewards in the brain. Many foods contain hidden sugar. Refined sugar has no nutritional value. Excessive sugar intake has been linked to diseases like diabetes, obesity, and heart disease. It can also cause tooth decay and weaken the immune system. Cutting back on sugar is important for health but may cause withdrawal symptoms.