Fats: Do they make you fat? They hurt? How many in the Diet?

Fats: Do they make you fat? They hurt? How many in the Diet?

Not everyone agrees on the “best” distribution of energy macronutrients to be adopted for slimming and health purposes .

In this article we will talk about the impact of fats on body composition and general health , trying to answer the questions that most frequently gravitate around the subject; that is to say:

  • Does too much fat make you fat? Are they more important than total calories?
  • Is fat bad for you? At what? Which? Why?
  • How much fat per day? What happens if I eat a few?
  • Are there fats that make you lose weight?

Does Fat Make You Fat?

The answer is not simple, as it is potentially misleading; however, to be honest, one could say no .

It’s not the fats that make you fat, but the caloric excess – possibly aggravated by an unintelligent distribution of energy macros.

However, it has been statistically demonstrated that hyperlipidic diets are associated with excess calories , thus promoting fat deposits .

Paradoxically, an excessive percentage of fat in the context of a hypocaloric diet offers more or less the same slimming effects as any other nutritional regimen aimed at reducing fat mass.

Conversely, an excessive percentage of fat in the context of a hyper- caloric diet aimed at muscle growth determines the inexorable increase in fat mass.

But why? Let’s find out.

What Makes You Fat More: Calories or Fat?

Why does too much fat make you fat? But when does fat not make you fat? What is more fattening: fat or carbohydrates?

The increase in fat mass is the consequence of a chronically positive caloric balance (food energy higher than that spent by the body in various activities).

This is because the excess of energy macronutrients , in particular of fats and carbohydrates , causes a series of reactions which promote the synthesis of endogenous fatty acids and their deposit in the adipocytes; more precisely:

  • raised insulin levels ;
  • loss of insulin sensitivity (in the chronic);
  • accumulation of Acetyl Coenzyme A in liver and adipose cells , and consequent lipogenesis;
  • increase in blood lipid transporters: chylomicrons and VLDL

Insulin is the anabolic hormone that allows the entry of glucose , amino acids, fatty acids, etc. in sensitive tissues.

Muscle and adipose tissue are among these but, while muscle can lose sensitivity to this hormone (due to chronic caloric excess and sedentary lifestyle), fat cannot – this is why insulin resistant people show a higher tendency to gain weight and they struggle to lose weight.

Insulin stimulation is due to the intake of energy macronutrients with meals and is greater as carbohydrates but above all as total calories increase.

The chylomicrons are the lipoproteins which, after having captured the long-chain fatty acids from the intestine , transport them both to the tissues and to the liver . Note : short and medium chain fatty acids , on the other hand, are released into the bloodstream without the need for lipoproteins.

When the total macronutrients are in excess (not only fats, but also carbohydrates), the liver cells accumulate Acetyl Coenzyme A – which should instead be used to produce energy (ATP) – and give rise to lipogenesis (synthesis of new fats) .

The fats synthesized by the liver are organized into VLDL (lipoproteins) and transported to the peripheral tissues, which can use them for energy purposes (especially muscles) or store them as reserves (adipose tissue).

Lipogenesis due to excess Acetyl- Coa also occurs in the same peripheral tissues.

Ultimately, it’s not exactly fats that make you fat, but rather excess calories and the association of the same with high levels of both fats and carbohydrates.

Are Fats Bad?

No , no fat is bad when taken in the right quantities.

Not even saturated and hydrogenated fats – constantly in the eye of the storm, due to their pro- atherogenic role – seem to have an indiscriminate harmful potential on the metabolism and, to a certain (small) extent, the same goes for trans fats – which we remember are also present in nature.

Yet, many studies show a positive statistical correlation between the consumption of ” bad lipids ” and the worsening of cholesterolemia . On the contrary, the percentage increase in “good fats” (omega 3, omega 6 and omega 9) seems to reverse this trend.

The studies, howevers, must be interpreted. In the sense that:

  • First of all, “the dose always makes the poison”;
  • Secondly, the subject’s metabolic efficiency needs to be considered; an obese person is always more subject to metabolic disorders than a person of normal weight ;
  • Last but not least, genetics also matter. Several metabolic alterations have a consistent hereditary predisposition; in that case, the diet may not play a determining role in the return of the blood parameters in question.

Ultimately, there are no fats to “banish” completely from the diet – also because it would be impossible. However, we must remember to prefer the unsaturated ones over the saturated ones, which have a better impact on the metabolism.

Are there any fats that make you lose weight?

No. _ There is no fat that makes you lose weight. All fats provide 9 kcal / g and none of them stimulates or optimizes lipid metabolism.

But then, why do we often hear that ” medium chain fatty acids make you lose weight?”

In reality, there are no valid reasons, but real conceptual distortions .

It is true that not all fatty acids are created equal. The presence or absence of double bonds, as well as the length, determine very specific characteristics and different metabolic impacts.

Short- and medium-chain fatty acids are absorbed and metabolized differently than long-chain fatty acids.

At the level of the intestine, after digestion, the short and medium chain fatty acids are released directly into the blood , making them “more rapidly metabolizable”. The long ones, on the other hand, first enter the lymphatic circulation, are stored in the chylomicrons and only later pass into the blood circulation.

Furthermore, the medium-chain fatty acids, once in the cell, can enter the mitochondrion without the intervention of the carnitine system . This aspect also benefits the speed of use.

They are all interesting features, but useless in practice, because the advantages of the latter are appreciable only in place of the others. At the dietary level it is completely impossible to structure a diet with only medium or short chain fats – unless you make the exclusive use of supplements .

Even the now inflated coconut oil , known for its alleged content of medium-chain fatty acids, is actually rich in lauric acid , which is metabolized as if it were a long-chain fatty acid and not a medium one.

How many in the Diet?

How much fat per day?

Considering all the bibliographic sources, the normolipidic intake enjoys a fairly wide range, which goes from a minimum of 10% to a maximum of 40%.

In Italy we consume an average of 20-35%, even if 25% is recommended for adults and 30% for growing subjects – about 0.8-1.2 g / kg of normal weight.

To avoid compromising the absorption of fat-soluble vitamins , some suggest not going below 15% even in diets for body recomposition.

Of all, obviously, the most abundant fraction must be of the unsaturated ones . Moreover, it is necessary to ensure the supply of essential fatty acids (AGE) and semi-essential omega 3 and omega 6 .

The total intake of AGEs must constitute 2.5% of total calories divided into:

  • 0.5% omega 3 (or 0.5 g to 1.5 g) – with EPA and DHA supplements for children, pregnant women, nurses and the elderly ;
  • 2.0% omega 6 (or 4.0g to 6.0g).


What happens if I eat a few?

Nothing , in the short term.

In the long term, however, reduced fat percentages can lead to:

  • Deficiency of essential fatty acids;
  • Lack of fat-soluble vitamins ( vitamin A , vitamin D , vitamin E , vitamin K);
  • Gallstones , constipation and other ailments;
  • Reduced efficiency of oxidizing them at the cellular level – recoverable by normalizing the diet.

What they are and what they are for

What are fats?

Fats, or rather lipids, are extremely important nutritional components for the organic balance of the “man machine”.

Although they have the same insolubility in water, solubility in organic solvents and greasy consistency, fats are extremely heterogeneous and differ in molecular structure and biological function.

The most widespread are fatty acids, which mainly have an energy and reserve purpose (when organized into glycerides); even if, as we will see, their type, total quantity and ratio in the diet can have a very different health impact.

What are fats for?

Referring to the entire category, lipids perform different functions; among them we mention:

  1. Energy (9  kcal /g)
  2. Cellular structural ( cholesterol  and  phospholipids  are essential elements for the structure of  cell membranes )
  3. Nerve structural (constituent of  myelin sheaths )
  4. Bio-regulator ( hormonal and parahormonal precursors )
  5. Vitamin solution ( fat-soluble vitamins : A, D, E and K)
  6. Reserve (  white and  brown adipose tissue )
  7. Essential , which concerns  Essential Fatty Acids  (AGE) or Essential Fatty Acids (EFA).

What are the most abundant fats in the diet?

The lipids of greatest nutritional interest are of the complex type, mainly formed by fatty acids and glycerol.

We are talking about glycerides , which make up about 96-97% of dietary fat; not surprisingly, glycerides are also the most present in the human body , as they represent the deposit form accumulated in adipose tissue.

Glycerides can be formed by one, two or three chains of  fatty acids  (FA), linked to an  alcohol  – more precisely  glycerol  – to form respectively mono, di or triglycerides – or mixed molecules such as phospholipids. The molecular component of glycerides that is used  directly  in order to produce  ATP  ( energy ) is constituted by AG.

In depth

Classification of fats

Lipids are ternary elements composed of carbon (C), hydrogen (H) and oxygen (O) and can be classified according to their molecular complexity:

  • Simple: Glycerides, Sterides and Waxes (esters formed by the bond between an alcohol and fatty acids)
  • Complexes: Phospholipids and Glycolipids (which also contain other molecules).

As anticipated above, the most relevant fats from a quantitative point of view are glycerides, more precisely the fatty acids they contain.

Fatty acids

Fatty acids are simple ternary compounds and occur as long carbon chains. They mainly have an energy function and, in glycerides, a reserve function. However, they are not all the same and, on the contrary, they can also differ quite significantly. The essential fatty acids are a particular exception, which are very important from a metabolic point of view and of which we will give a brief overview below.

Types of fatty acids

AGs differ in length – short, medium or long chain – and in the type of bonds that characterize them. Saturates have no double bonds, monounsaturates have one double bond, and polyunsaturates have two or more double bonds; mono and polyunsaturated are enclosed in the group of unsaturated.

The double bonds determine its chemical-physical characteristics such as: consistency based on temperature – the unsaturated ones are liquid at room temperature while the saturated ones have a solid consistency – heat stability and smoke point – for food ones – sensitivity to peroxidation etc.

Essential Fatty Acids

Essential lipids, i.e. elements that the body is unable to synthesize on its own, are called Essential Fatty Acids (AGE) or Essential Fatty Acids (EFA). They appear as simple carbon chains and both have 2 or more double bonds (polyunsaturated AG); they are called:

  1. Alpha linolenic acid , from the omega 3 series, mostly contained in oily fish and soybeans
  2. Linoleic acid , from the omega 6 series, mostly contained in olive oil , sunflower , corn , grape seeds and soy and in good quantity in dried fruit .

AGEs perform some very important functions such as:

  • Nervous and ocular development
  • Membrane fluidification
  • Transduction of membrane signals
  • Interactions between cells
  • Precursors of pro- and anti-inflammatory eicosanoids
  • They influence the immune system , for the synthesis of prostaglandins
  • Docosahexaenoic acid ( DHA) improves nitric oxide synthesis , is anticoagulant and antiplatelet
  • Omega 3s generally reduce triglyceridemia and blood pressure if in excess
  • AGEs positively influence cholesterol levels, usually by increasing HDL (High Density Lipoprotein – good cholesterol ) levels .

Other less evident effects of omega 3 are: protective action on the nervous system in old age, beneficial role in moderating depressive symptoms, etc.


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