Usually, these factors are inter-related. For this reason they cannot be judged separately. Nevertheless, there are some characteristics to be noted:

Age

Children need more nutrients to help them grow healthy: increased amounts of foods rich in vitamins, minerals and calcium and also protein. The most important measure is to direct them to a healthy diet, emphasising fruit, vegetables and dairy products. The tendency to eat too many sweets and processed foods should be curtailed.

Old people need more liquids and a diet rich in calcium to help preserve bone health and prevent osteoporosis, a major risk for people over the age of 50. The diet should include milk and dairy products, fish with soft bones, nuts, dark green leafy vegetables and fortified bread.

Gender

Some health risks, such as osteoporosis and iron deficiency, are more prevalent in women. Women should pay special attention to their diet and try to eat a variety of foods. They should maintain a healthy weight, and eat fewer fats, cholesterol, sugar, salt and alcohol. The diet should rely mainly on vegetables, fruits, grain and dairy products.

Also, pregnant women have special dietary needs, such as supplementary calcium, vitamins, minerals and water. Folic acid must be supplemented even before pregnancy.

Activity

Calorie intake needs differ, depending on lifestyle and activity. Thus, persons with intense physical activity and teenagers and adolescents will need supplementary amounts of energy-providing food, such as carbohydrates. The recommendation for a healthy carb supplementation would be that the carb intake must be a healthy one. Complex carbs, such as whole grains, for example, should prevail over simple carbs (sugars and refined bakery products).

Physiological state

Special attention should be paid to particular cases. These include illness, or recovery from illness, whether the body has some deficiencies in essential substances (such as vitamins, minerals, iron). Take into account seasonal and other factors that could influence your diet and make it deficient.