Why You Need Carbs, Protein & fat
Carbohydrates are the body’s major source of energy or fuel. Carbohydrate energy can only be used by the body in the form of glucose. ‘Blood sugar’, the sugar in our blood that is available for immediate use as a fuel for energy, is in the form of glucose.
All starches, when eaten, are broken down by the digestive system into smaller starches called polysaccharides and disaccharides then eventually into monosaccharides.
It is only the monosaccharides, the simple sugars, which are absorbed by the gut and used, in the case of glucose, directly as energy, or taken to the liver and converted to glucose to be used as energy.
Proteins are the building blocks of the body and are required to build every cell in the body. Even blood and nerve cells have protein in their structure. Other substances in the body are also complex or specialised proteins; enzymes (which make things happen), hormones (chemical messengers), antibodies (immune fighters) and the DNA at the heart of each cell (biological blueprint).
Even the digestive enzymes that break down protein in food so that it can be absorbed into the bloodstream, are themselves specialised proteins.
Proteins are broken down by the digestive system into small molecules known as amino acids, and it is in the form of amino acids that the body can absorb and use protein.
There are 23 different amino acids in nature and all proteins are made up of different combinations and different proportions of these.
The body is also able to convert some amino acids into others. Of the 23 amino acids, there are 8 which must be present in your diet.
In other words, they are essential, and cannot be made from other amino acids in the body. Provided the body obtains these 8 amino acids in the diet, it can make any proteins or amino acids that it requires.
Animal proteins (meat, fish, eggs, milk) contain all 8 essential amino acids and are thus known as ‘complete’ proteins.
Plant proteins are incomplete because they lack one or more of the essential amino acids (except soy protein which is complete).
Provided vegetarians eat a very varied diet which includes the different types of plants (grains, pulses/legumes, nuts and seeds), then they too will obtain all 8 essential amino acids.
When we think of fat in the body we tend to think of ‘adipose tissue’, the layer of fat underneath the skin which we refer to as body fat.
This is an important energy store for the body and serves and insulates against the cold. A growing number of people in the west are overweight and obese, carrying excess body fat to an extent that is unhealthy for the body.
But fat is much more important to the body than just an energy source and warmth. Fat from our food is essential to health.
Fat is the major component of cell membranes (cell walls) in every cell in the body, fat is necessary for brain function, nerve transmission, the immune system and for making hormones. Fat is vital to health.