Fats in our diet: Function, Types and Foods

types of fats

We will explain to you what are the essential functions of lipids in the body, how they are metabolized, what types of fats there are and which ones are most beneficial.

The lipids are a rather heterogeneous organic molecules composed of group hydrogen, carbon  and, to a lesser extent oxygen , but may also contain other elements. Usually, it is usually wrong to call lipids fats , although fats are actually lipids from animals. What this group of biomolecules have in common is that they are insoluble in water and soluble only in organic solvents such as benzene or chloroform.

Functions of fats in the body

The fats are absolutely necessary to perform different functions within our body, some of which are:

    1. Energy: They are the main energy reserve of our organism.
    2. Structure:  They form part of the cell membranes and cover the organs for their protection.
    3. Biochemistry: They stimulate some chemical reactions of the organism as precursors in the synthesis of some vitamins , hormones, acids, etc.
    4. Transport:  Lipids serve as vehicles for transporting liposoluble substances in the small intestine.

Metabolism of fats

Like all other nutrients we eat with our diet, fats must break down into smaller molecules that the body can assimilate. The proteins are broken down into amino acids , the carbohydrates glucose, and lipids into fatty acids and monoacylglycerols to be absorbed and used as energy reserves in the body . The first step in the digestion of fats occurs in the stomach, since the agitation favors the appearance of emulsions that begin the digestion of fats. When they enter the intestine, they mix with bile and enter into action pancreatic enzymes, called lipases, that act on the lipids to break them down into assimilable molecules.

Once absorbed in the intestine, fats will travel through the body in the form of lipoproteins , which are water-soluble molecules that allow the distribution of fats through an aqueous medium such as blood.

Types of Fats

Depending on whether they contain in their molecular composition fatty acids or not, fats are divided into two groups :


They are those that do not contain fatty acids in their composition. In this group we find the terpenoids, steroids, etc.


They are fatty acids with two subdivisions :

    • Simple : They are those that only contain carbon, hydrogen and oxygen. These include fats (solid at room temperature), oils (liquids at room temperature) or waxes.
    • Complexes : They are those that also contain other elements, such as nitrogen, sulfur, etc. In this group we find phospholipids, glycolipids, etc.

Fatty acids

The fatty acids are saponifiable lipids formed by fatty acid base units. These acids are composed of long chains of atoms that, depending on whether or not they have double bonds, are divided into:

Saturated Fatty Acids

This group does not have double bonds and, because they have all their link points already occupied, is why they are called “saturated”. These types of acids are very complicated to digest and tend to accumulate and form plaques in the arteries and other corners of the body. The animal flesh is rich in saturated fatty acids, as well as milk .

Saturated fatty acids are rich in arachidonic acid, precursor to prostaglandins PGE2, hormonal substances that, being necessary in a certain amount, their excess can lead to inflammatory processes and allergies , besides accumulate in the arteries and produce high levels of cholesterol and cardiovascular problems.

Unsaturated fatty acids

This group does have double bonds and is a type of acid that is easier to metabolize. They are what we know as oils and constitute a much more beneficial type of fat . They are divided into:

Monounsaturated fatty acids. They are the family of Omega 9, rich in oleic acid, found, for example, in olive oil

Polyunsaturated fatty acids or essential fatty acids . They are the family of Omega 3 and Omega 6, rich in linoleic and alpha-linolenic acids (precursor of EPA and DHA) found in fish oils, leafy vegetables, seeds and oleaginous nuts.

Trans fatty acids

They are fats that have passed from their natural form cis- to an artificial ” trans ” form from an industrial process. That is, trans fats do not exist in nature.

Unsaturated fatty acids (mono and poly), so beneficial to the body, are very delicate in the oxidation process , so that heat and some industrial processes cause important changes in their molecular structure. Trans fats are generated from vegetable oils subjected to industrial processes such as hydrogenation . When a fat is hydrogenated or subjected to high temperatures, the molecules are transformed and become something like a saturated fat that can not be integrated into the metabolic chains (as if they were defective parts). These types of fats do not exist in nature and the body treats them as foreign agents that it does not recognize, so they increase the level of toxics within the body.

Any hydrogenated or partially hydrogenated fat carries inflammatory processes and is truly harmful to the liver and heart . Fats or trans fatty acids are found in foods such as margarine, industrial pastries, fried foods and processed products , filled with additives .

Essential Fatty Acids

Our body  can synthesize all saturated and monounsaturated fatty acids (from proteins, alcohols or carbohydrates) except two groups of polyunsaturated fatty acids that must necessarily incorporate through the diet and that is why they are known as essential fatty acids : the family of Omega 3 and Omega 6 , as we have seen.

These fatty acids are part of cell membranes , so when our cells have good levels of essential fatty acids, they remain healthy and flexible and facilitate the proper exchange of nutrients . In addition, these essential fatty acids are precursors of prostaglandins PGE 1 and PGE 3 , highly beneficial hormonal substances that regulate numerous functions within the body.

On the contrary, a diet deficient in Omega 3 and Omega 6, can cause the weakening of the immune system and lead to the appearance of numerous diseases or deficiency.

We must also take into account the importance of the relationship between both , since often an imbalance is often given in favor of Omega 6 and to the detriment of Omega 3 . Check your functions, food and balance between both in our report what are essential fatty acids .

Fats and cholesterol

The cholesterol is a type of fat that can be manufactured internally or ingested with food, although in the latter case the percentage is lower and the amount of cholesterol in blood depends fundamentally on our domestic production. Cholesterol is essential to develop different functions and chemical reactions within the body, as it is a precursor of hormones, bile acids or vitamin D , is part of the cell membranes and repairs fissures of circulatory walls.

The liver is responsible for creating these molecules, called lipoproteins . Depending on their density, these lipoproteins take one name or another.

Low density lipoprotein cholesterol , or DLD (what we call bad cholesterol ), are the molecules that travel from the liver to the places where they are needed. High density, or HDL ( good cholesterol ), are the molecules that collect excess cholesterol and return it to the liver to be metabolized or expelled.

To carry out a balanced diet, the WHO recommends a daily intake of fats of between 10 and 30%, being those containing polyunsaturated fatty acids (essential fatty acids) which should be more abundant and trying to minimize Saturated fats and trans fats.

The truth is that, although cholesterol has a very bad reputation, the scientific studies deny certain myths about cholesterol and corroborate that their food intake does not have great repercussion compared to their endogenous production. In addition, they point out other factors (such as smoking, lack of exercise or excessive consumption of sugar and diabetes ) much more decisive when developing cardiovascular diseases.

If you are the type of person who measures the amount of fat that food contains for fear of gaining weight , remember that there is nothing more effective to lose weight than to follow a balanced diet , moderate exercise and surrounded by loving people who provide us with support.

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