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Basic nutritional requirements
Last reviewed: 04.07.2025
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Proper nutrition is aimed at achieving and maintaining a desirable body composition and maintaining a high potential for physical and mental work. Balance between energy intake and energy expenditure is necessary to maintain body weight. Energy expenditure depends on age, gender, weight, metabolic and physical activity. If energy intake exceeds energy expenditure, weight gain occurs. If energy intake is less than energy expenditure, weight loss occurs.
Daily requirements for essential nutrients also vary with age, gender, weight, metabolic activity, and physical activity. Every 5 years, the U.S. Department of Agriculture (USDA) Office of Nutrition and Food Science of the National Academy of Sciences/National Research Council issues dietary guidelines that include recommended intakes of protein, energy, and some vitamins and minerals (RDAs). For lesser-known vitamins and minerals, safe and adequate daily intakes are listed.
Pregnant women and infants have special nutritional needs.
The USDA publishes a Food Guide that lists the recommended daily intake of various food groups. Some nutritionists recommend eating more fruits and vegetables. A separate food reference pyramid has been created for older adults, for whom there are separate nutritional requirements. Adequate fluid intake is the base of this pyramid.
Portion sizes
Food group |
Serving size |
Bread, cereals, rice and pasta |
1 slice bread 1 ounce* ready-to-eat cereal 1/2 cup cooked cereal, rice, or pasta |
Fruits |
3/4 cup fruit juice 1 medium apple, banana, or orange 1/2 cup chopped, cooked, or canned fruit |
Meat, poultry, fish, eggs, dried beans and nuts |
1/2 cup cooked dried beans 2-3 ounces cooked lean meat, poultry, or fish (1 egg or 2 tbsp peanut butter equals 1 ounce lean meat) |
Milk, yogurt and cheese |
1 cup milk or yogurt 1.5 ounces natural cheese 2 ounces processed cheese |
Vegetables |
3/4 cup vegetable juice 1 cup fresh leafy vegetables 1/2 cup other vegetables, cooked or freshly chopped |
1 ounce - 28.349 g.
Fats should make up about 30% of total calories, saturated and trans fatty acids - less than 10%. Excessive consumption of fats, including saturated ones, increases the risk of developing atherosclerosis. Replacing saturated fats with polyunsaturated fatty acids can reduce the likelihood of developing atherosclerosis. Routine use of food supplements is not necessary or helpful; some supplements can be harmful.