Eating nutritious food is important at every age. For children, a healthy diet with the right serving sizes ensures proper growth and development. As you get older, you need to eat healthy to give your body energy throughout the day and to ward off health issues such as diabetes, heart disease, and other health conditions.Everyone's nutritional needs are different, says Denver-based dietitian Jessica Crandall, RD, CDE, a spokeswoman for the American Dietetic Association. For example, a pregnant woman needs more calories than an 85-year-old man. A teenager needs more protein than a younger child.Age, height, weight, and activity level, as well as any health conditions, impact nutrient and calorie needs, but if you cook for a family, it can be difficult to make sure everyone's meeting their daily quota.