Most people are afraid of including fat in their diets. In this post, we go through the different types of fats in foods and how should the perfect fat intake be.
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Fats are biomolecules containing a fatty acid attached to a glycerol (source).
Fats must contain one or more fatty acid, but the structure is what differs between different types of fats.
Properties of Fats
To understand the importance of fats in our organism we first need to look at the properties of this molecule.
Fats contain a non-polar fatty acid (hydrophobic), and polar head (hydrophilic). The fatty acid chain will do everything to avoid water interactions. On the other hand, the polar head will attract water.
The Functions of Fat in Our Organism
Fats are important molecules in your organism. There are some fats called "essential fatty acids", and you'll need to take them through diet.
A correct fat dietary intake will make sure that all these functions are working perfectly, optimizing your metabolism.
Constituents of the cell membrane
The cell membrane is formed by a lipid bilayer. The hydrophobic chain attract each other forming the inner core of the membrane.
The polar head will face the outer and inner environment, interacting with water.
Precursors of Steroid Hormones
Cholesterol is the precursor of all steroid hormones. If don't have enough cholesterl, your hormonal environment will be deffective.
If you have too much cholesterol, the risk of cardiovascular disease explodes (study). For a 1% reduction of cholesterol, there's a 2% reduction in coronary heart diseases (study).
But that doesn't mean cholesterol is bad for you. You need to balance your diet to achieve the correct and healthy levels of cholesterol.
Energy Storage
Fats, make up the main and largest energy storage in your body. When there's glucose available for energy production, triglycerides are stored in adipocytes, also called 'fat cells'.
Obese people with 15-20kg of adipose tissue could meet their energy needs for months just from the fats stored in these cells. Glycogen stores, on the other hand, don't make up more than one day of energy needs (source).
When glucose and glycogen are not available, triglycerides are hydrolysed, transported, and oxidized to produce energy. This is the basic principle of fat loss.
Different Types Of Fats In Food
Not all fats are the same. Depending on the structure and nature of the fatty acids, we can talk about:
- Monounsaturated fatty acids
- Polyunsaturated fatty acids
- Saturated fatty acids
- Trans fats
Monounsaturated Fats
Monounsaturated fats contain one unsaturation on their fatty acid chain (source). Monounsaturated fats are olive oil, peanuts, avocado, nuts, and seeds.
Intake of monounsaturated fats reduce the risk of cardiovascular diseases and all-cause mortality by 11% (systematic review) (study).
These fats also play a role in carbohydrates metabolism. It lowers plasma concentrations of glucose and insulin. This means an improvement on the development of diabetes and other metabolic diseases (study)
Polyunsaturated Fats
Polyunsaturated fats (PUFAS) present more than one unsaturation on their fatty acid chain (source)
There are three types of PUFAS: ω-3/6/9(source). Only the ω-3 and ω-6 are completely 'essential fatty acids'.
PUFAs produce metabolites related to the inflammatory state: eicosanoides, prostaglandins, tromboxans,...
While the metabolites derived from ω-6 are pro-inflammatory, the ones derived from ω-3 are less pro-inflammatory or anti-inflammatory.
Western Diets are generally high on ω-6 and low on ω-3. This promotes a chronic inflammatory state, related to higher risk of cardiovascular disease, diabetes, muscle dysfunction, allergies, and weaken inmune response (study).
Higher intakes of ω-3 and a lower ratio ω-6/3 can tremendously improve your health. It lower the risk cardiovascular disease (study), improves cognitive function and working memory (study), modulates the inmune system (study), and promote a better gut microbiome composition and richness (study)
Saturated Fats
Saturated fats don't contain any unsaturation on their fatty acid chain. All the carbons are "saturated".
There's quite a lot of controversial scientific evidence regarding the effects of saturated fats in our health (study) (study)
Intake of saturated fats increase LDL, but the LDL formed is rather large than the small and light particles related to cardiovascular disease (study).
A controlled intake of saturated fats shouldn't be a problem for your health.
U.S Guidelines recommend to limit the intake of saturated fats to ≤10% the total calorie intake, or ≤20% the total fat intake (study). Foods containing saturated fats are fatty meats, butter, bacon, whole milk, cheese,...
Trans Fats
Trans fats are the execption to the rule. They are monounsaturated fats, but with a 'trans' double bond instead of the 'cis' double bond.
To improve the shelf-life and stability of unsaturated fats, they were partially hydrogenated in the industry.
This converted most of 'cis' double bonds into single bonds, increasing the melting temperature and shelf-life. But it also converted some 'cis'-bonds into 'trans'-bonds (study)
Recommended Fat Intake
Mono and polyunsaturated fats can contribute and improve our health and inflammation.
Saturated fats may may not be as bad as we though, but there's not enough evidence yet to confirm anything.
Last, but not least, trans fats. Simple and clear... avoid them
Science-based recommended fat intake:
Base your fat intake on mono-/polyunsaturated fats, limit the saturated fats and totally remove trans fats.
Conclusion
Fats are one of the three macronutrients of your diet. In your organism, they play important roles forming the cell membrane, synthesizing and mantaining the hormonal environment, and being the largest long-term energy storage.
In this post we've seen the different types of fats and the benefits and/or adverse effects on our health.
Base your fat intake on mono-/polyunsaturated fats, limit the saturated fats and totally remove trans fats.
