We know that fats are commonly divided into "good" fats and "bad" fats. From a chemical point of view, we are talking about lipids, i.e. macromolecules which, together with proteins and carbohydrates, are one of the three essential nutrients in the human diet. They can provide the body with a lot of energy: 1 gram of fat contains 9 kilocalories, twice as much as other macronutrients.
Precisely because of their calorie content, we tend to eliminate them from our diet. On the contrary, however, it is important to maintain the right amount of them for their important functions, but it is equally important to know how to distinguish between them in order to use them in a balanced and healthy way.
Eating more fat does not necessarily mean gaining more weight; weight gain is primarily determined by how many calories are consumed. Chronic calorie excess leads to weight gain, which in turn leads to:
- increase in blood fats, which in turn can lead to atherosclerosis and therefore obstruction of the blood vessels;
- accumulation of abdominal fat, a benchmark for cardiovascular risk;
- alteration of the hormonal profile;
- fatty liver: the liver (the body's metabolic centre) undergoes a disruption of its cellular architecture; which corresponds to an alteration of its numerous functions and therefore to systemic damage.
Fats are therefore classified as good or bad macronutrients depending on whether or not the molecule contains unsaturated bonds:
- saturated fats are commonly referred to as "bad" fats, and are mainly found in processed meats, chicken skin, fried foods, packaged foods, butter, cream and margarine. When these fats are in excess, they tend to raise LDL cholesterol levels and thus promote the onset of cardiovascular disease. LDL cholesterol can accumulate in the walls of arteries, obstructing blood flow and causing inflammation, which leads to stiffening of the blood vessel and the risk of clot formation;
- unsaturated fats are usually referred to as "good" fats and are divided into monounsaturated (e.g. oleic acid) and polyunsaturated (e.g. omega-3) fats, depending on whether they have one or more unsaturated bonds. They are more prevalent in plant-based foods such as olive oil, sunflower oil, peanut oil, nuts (omega-3, omega-6) and oily fish (omega-3). These fats promote good health, cellular stability, increased levels of "good" HDL cholesterol, and reduce the risk of cardiovascular disease.
Lipids, as we said, perform various functions:
- they are a reserve of energy, in the form of adipose tissue;
- provide thermal insulation and protect against impact;
- they are precursors of hormones;
- they play a structural role, as they are an essential component of cell membranes (phospholipids, cholesterol);
- they transport the fat-soluble vitamins A, D, E and K, which the body needs for various metabolic processes;
- they give palatability.
The recommended daily intake of fat varies depending on energy requirements: generally, it covers 20-30% of daily energy intake. For example, in a 2,000-kilocalorie diet, this percentage corresponds to 44–78 grams of fat per day.
It would be preferable to distribute this amount among the various fatty acids as follows:
- Saturated fatty acids: < 10%
- Monounsaturated fatty acids: 10–15%
- Essential omega-3 fatty acids: approx. 0.7%
- Essential omega-6 fatty acids: 2.5–9%
The Western diet has a significant imbalance between omega-6 and omega-3 fatty acids, generally being too rich in omega-6 fatty acids, mainly found in meat, and poor in omega-3 fatty acids. This imbalance increases inflammation, which is linked to the risk of cardiovascular disease, diabetes and other chronic conditions.
Some tips for balanced use of lipids:
- use extra virgin olive oil in cooking;
- replace saturated fats with unsaturated fats: for example, use avocado, tahini, nuts or seed butter instead of dairy butter;
- eat fish, especially oily fish, twice a week;
- eat meals based on legumes or beans at least twice a week;
- choose lean meats and remove visible fat;
- use dried fruit as a snack or add it to dishes (e.g. salads).
Some examples to include in the menu: porridge made with oat flakes, yoghurt; toast with oilseeds, smoked salmon and baby spinach; pear and dark chocolate; roasted carrot hummus with cashews and seeds; guacamole and egg bowl; pear salad with black beans and walnuts.
In addition to favouring unsaturated fats, it is advisable to limit the use of fats during cooking: it is better to choose cooking methods such as baking in foil, roasting or steaming, and to season food raw with a moderate amount of extra virgin olive oil. Among vegetable fats, it is preferable to avoid consuming margarine, which is rich in hydrogenated fats. As for animal fats, it is important to remember that the type of farming and feed used affect the quality of the lipids found in meat, milk and dairy products: it is always better to choose products from non-intensive farms. In the case of fish, wild-caught fish usually has a better lipid profile than farmed fish.
It would be useful to always check the labels on the food we buy, looking not only at the “fat” content, but also at the “saturated fat” content, without forgetting that nutrition should always be considered as a whole. For example, if you occasionally eat fried foods, try to use peanut oil, which has a high smoke point that limits the development of harmful compounds. Last but not least, when talking about fats, it is important to remember that physical activity has the power to raise levels of "good" HDL cholesterol in the blood.
(Article by Dr. Giulia Daniotti)
