Foods provide various substances that are the “raw material” for building cells. The cells produced allow the growth, development and maintenance of the body by replacing the dying cells.

Foods also act as “Fuels” In our bodies: Some molecules in food are “burned” during cellular respiration and provide the energy needed for organ activity.

The food we eat usually consists of a mixture of substances. Among them, we highlight the Water, the mineral salts, at proteins the carbohydrates, the lipids and the vitamins. All of these substances are necessary for the maintenance of life.

The water

Water is the most abundant substance in the constitution of living beings. The adult human body is roughly composed 65% of water. This substance enters the composition of cells and hence tissues, organs and systems. It is also the main substance of intercellular materials, such as blood plasma.

Daily we eliminate water with the urine, at feces, O sweat and also in the form of breath by breath. The amount of water lost by a human being may vary under certain conditions. This loss is on average of:

  • 1000 to 1500 grams of urine;
  • 100 grams for the feces;
  • 500 grams for sweat;
  • 400 grams by the exhalation.

We compensate for the loss of water by drinking it directly or by eating it with food. Milk, juices, fruits and vegetables are foods that contain a relatively large amount of water.


Also known as glycidesCarbohydrates are foods that generally have energy function in the body, that is, they act as "fuels", providing the energy needed for the activities of cells.

The main sources of carbohydrates are sugar (sweets, vegetables and milk), cereals and the grainsTherefore, they are found in fruits, honey, cornflakes, oats, granola, rice, beans, corn, popcorn, flour, breads, cakes and other pasta.

There are several types of carbohydrates: glucose, fructose, sucrose, lactose, starch among others.

  • THE glucose and fructose, found in honey and various fruits, are relatively small molecules and can easily be absorbed in the gut.
  • THE sucrose, extracted from sugar cane and beet, is formed by the union of two smaller carbohydrates: glucose and fructose.
  • THE lactose is found in milk and is formed by the junction of two smaller carbohydrates: glucose and galactose.

O starch It is a very large molecule, formed by the union of hundreds of glucose molecules. It is the natural energy reserve of plants and is not sweet. It is stored in large quantities in certain roots (cassava), certain stems (potatoes) and in various grains (wheat, corn and beans). So when we eat sweets and pasta we are eating different types of carbohydrates.

Carbohydrate absorption is quite rapid and energy is available to the body immediately after ingestion. But likewise, their reserves run out about half a day after their last meal. Theoretically, we could live perfectly without them, extracting the necessary energy from fats and proteins. But both in taste and ease of absorption, more than half of all of our diets are carbohydrate.

And how do carbohydrates generate energy? Firstly, they must be converted to glucose in the liver to be later transformed into energy by the cells.

The difference between sugars and starches is that sugars and starches are simpler and therefore absorbed more quickly by the body. Ideally, preference should be given to starches, as foods high in sugar can cause inadequate insulin secretion, a hormone that stimulates glucose uptake in cells. Another good advice, experts say, is to avoid refined carbohydrates like sugar and white rice. In the refinement process, a large percentage of fiber and nutrients is removed from the food. This is why wholegrain has higher nutritional value.

In fact, every gram of carbohydrate provides 4 kcal. So for those who want to lose weight, the best way to cut calories is to cut out candy and soda, which are high in carbohydrate products but have no other nutrients.