Why do we eat?

What is the purpose of eating?

We could answer this question  in many ways: eating fulfills our nutritional needs, but it is also a pleasure able to satisfy our social, cultural, emotional and psychological needs.

From a nutritional perspective the ultimate purpose of eating is to provide energy and essential compounds (i.e. compounds that we cannot produce and we need to acquire from the food) for the functioning of our body.

We have to consider our body as a biological machine which requires: 

•   continuous supply of energy (in forms of carbohydrates, fats and proteins);

• compounds necessary to synthesize structures vital for life (e.g. essential amino acids for proteins, fatty acids for cell membranes and hormones, etc.) and to sustain our physiology (e.g. vitamins, minerals).

Food is the only source of energy we have. Our body is designed to convert the chemical energy of foods into usable energy to performed pivotal functions, such as muscle contraction, synthesis of macromolecules, etc..

The energy provided by food can only be transformed and used at cellular level. In order to do so, food has to be processed by our body, that means: 

1. digestion in its monomeric components (e.g. carbohydrates broken down into glucose, proteins in to amino acids, lipids into fatty acids), 
2. absorption of monomers by the intestinal tract, 
3. and delivery of monomers by the blood vessels to any single cell of the body.

Food monomers can be used as fuel to generate energy only when they are inside cells; moreover cells of different tissues and organs have distinct fuel requirements. We can call this process as CELLULAR NUTRITION. 

We will talk about that next time.

Ciao