Foods represent one of the life basic needs:

• proteins (the main role is to regenerate tissues and to form new cells),

• lipids or fats (the main role is to release energy),

• carbohydrates (with role in releasing energy immediately),

• minerals (sodium, potassium, calcium, iron, phosphorus, sulfur, iodine, copper, zinc, cobalt, fluorine, magnesium) - without them the body couldn't survive -,

• vitamins (our body couldn't produce vitamins, they are assimilated from foods),

• water (it has no calories, and is essential for life).

For example a person that has 70 kg weight, in his body are included 43 l of water (11.5 l are extracellular water and 31.5 l are intracellular water). For a better view I'll explain this in percent: 70% from body weight is made from water (50% intracellular water, 20% extracellular water).
 

For a correct eating we should know about:

• proteins: they can be of animal and vegetable origin, and must be introduced in the diet in percentage of 20-25% from caloric value of daily global food, of which 50% should be animal protein with high biological value;
• carbohydrates - these must form 40-50% from total caloric value. To have an ideal weight we should eat carbohydrates as: seeds, cereals, tubers and avoid bad carbohydrates as: sugar, sweets;
• lipids - these form 25-30% from ordinary foods.

The quantity of needed food is measured in calories. The calories need will vary depending on: age, geographical factors, work and sex. For example for a man of 30 years, weighing 70 kg: a sedentary job, an office work will bring him a caloric need of 30 calories/kg (2100 calories for 24 hours), an easy work brings him 35 calories/kg (2450 calories for 24 hours), a hard work will bring 40 calories (2800 calories in 24 hours), and a very hard work brings 45-50 calories/kg (3350 - 3500 calories 24 hours).


Tips for a correct eating:

• eat so as not to exceed with 15% and to lose with 10% your ideal weight;
• if you have a gain weight tendency avoid: white bread, farinaceous foods, fats;
• beware of poorly prepared foods (fried foods, spicy sauces);
• avoid to eat animal fats and concentrated sweets;
• avoid heavy meals and alcohol, try to walk 15-20 minutes after every meal.