Dr Guy-André Pelouze

Why Fatty Foods Do Not Have to Mean ‘Getting Fat’: An Explanation of Human Metabolism

It sounds intuitive: eat food-containing fat, and you will get fat. And yet it simply is not always true. For many people, this is very difficult to grasp, because this principle, this assertion is intuitive.  And as is usually the case, the intuitive always seems to override the actual facts.

Unfortunately, biology is not there to be simplistic.  It teaches us that it is not the fat that we eat that will be deposited in our arteries.  Indeed, there is no clear established link between the cholesterol that we eat, between the fat that we ingest and what gets deposited or not in our arteries.  Why?

Metabolic machine

It is actually quite easy to understand.  In between what we eat and our arteries, there is a massive metabolic machine to begin with.

The liver reconverts, reconfigures, and readjusts everything we eat after it has been digested by the digestive tract, in such a way that our needs are met. This metabolic machine makes little droplets in the bloodstream to transport fat towards peripheral tissues, in order to use it, produce energy, create membranes, produce hormones…  The liver regulates all this.

The liver as conductor

The second point that needs to be taken into consideration is that the liver is capable of transforming sugar into fat in a situation of surplus calories.  Now, what do we eat in great quantity today?  Starch: bread, pasta, wheat, corn, a certain number of cereals for breakfast etc.  All this represents much more than 50%, sometimes 60%, or even 80% of sugar, of carbohydrate. This is being discussed more and more, in dietary circles that the focus should not be on fats, but rather on sugar.
What does the liver do in the face of this situation of flooding?  It converts, slowly but surely, this carbohydrate into lipid, these little droplets that it then sends into the adipose tissue.  So much so that you can eat very little fat and nonetheless produce masses of triglycerides, that is fat, through the liver.  This is where lies the failure of all that is low-fat – that is light, without fat, without palm oil – because in reality, by substitution effect, we are often compelled to replace the fat by carbohydrate.

Low-fat is tasteless; because taste is often carried by fat.  Thus, to compensate for the lack of taste, we add carbohydrate, sugar. The body needs the intake of balanced fats that you can find in palm oil (50% saturated fats and 50% unsaturated) and substituting it with carbohydrates and sugar is not healthy for the body. It is a mistake to want to replace fats by carbohydrates or sugars that are real source of calories. This should be a warning: do not trust the foods where you read ‘no palm oil’ or ‘no fat’. It may sound enticing, but will not make you healthier. It is simply spin from the companies involved, without any science.



By Dr Guy André Pelouze

Dr Guy-André Pelouze is a French cardio-thoracic surgeon, and a founder of the French think-tank and research group Institut de Recherche Clinique (Institute of Clinical Research). Dr Pelouze is a widely quoted writer and commentator on health and nutrition in France, and is the founder of the Food Facts Index, an independent website focusing on food-related issues in both French and English.