Healthy eating is a crucial part of keeping us healthy. For good health, we need more than 40 different nutrients, and no single food can supply them all - we need a wide variety of foods. Poor, unbalanced diets are one of the greatest public health challenges of the 21st century. Whatever our personal approach to diet may be, healthy eating is about balancing our choices over time. Healthy eating is most effective if accompanied by good hydration, sufficient sleep, and enough physical activity.