On the subject of macronutrients, entire textbooks can be written. Many volumes can be written on the subject of carbohydrates alone and how they react in the human body. The average person does not need to know the scientific detail about carbohydrates, but you do need to know enough about them so that you can make informed choices about your food, which will have gigantic positive benefits for your life.
The average human body can store a few hundred grams of reserve carbs in the muscles and liver, to be used as instantly accessible fuel. Once you consume more carbohydrates than the body can store in its limited reserves the sugars are very easily converted into fat and stored in your body, using insulin as the chemical pathway.
These carb reserves are depleted after about 12 hours of fasting, and when this happens the body has to seek its natural energy source, being its fat reserves.
You can think of carbohydrates as a supply of sugar to the body, or more accurately glucose. This glucose can be used as a fuel for the body’s cells, but most importantly for the brain. The body has a built-in biological mechanism to supply the brain with fuel, regardless of the amount of carbohydrates consumed in the diet.
Of all the macronutrients – being carbohydrates, proteins, and fats – carbohydrates are the least necessary macronutrient to be eaten. Indeed, your body can function very happily, and actually at its healthiest, for the term of your life, if you make a conscious effort to restrict the carbohydrates to the levels that you would naturally eat in vegetables, fruit, nuts and dairy. Your body can function quite happily on 25g to 50 g of carbohydrates per day.
This is the level that we recommend that people target if weight loss is their goal, or if they are very overweight. Once you have reached your desired weight, you can be more liberal with carbohydrates.
Ironically, when we say that carbohydrates are the least necessary macronutrient to be eaten, the average person’s diet contains more carbohydrates than any other macronutrient. The human body has evolved over a period of millions of years, and only in the last hundred years have carbohydrates been so abundant. Your body is simply not designed to consume the levels of carbohydrate predominant in the Western diet, and as a consequence the body becomes obese, diabetic and subject to all manner of illnesses.
Carbohydrates cause the greatest spike in insulin, and constant bombardment of carbohydrates in our food causes insulin to be present in higher and higher levels in the body. The body then becomes “insulin resistant”, which is the cliff which millions of people have fallen off – leading to the abyss of obesity and the associated diseases of modern living.