Dr. Sudha Tiwari emphasizes the importance of a balanced diet containing all food types in the right proportions for optimal health, including cereals, fruits, vegetables, dairy, and proteins. She highlights the nutritional benefits of each food group, the essential nutrients they provide, and the risks of consuming junk food, which is often low in nutrients and high in unhealthy components. The document advises focusing on healthy food choices, with water as the preferred beverage, to promote overall wellness.