In the previous article we discussed blood sugar, insulin and how they cause us to gain fat. In this article we will continue by discussing the different types of sugars that carbohydrates break down into. By understanding the different types of sugars that we are exposed to and how they differ metabolically will help us gain more understanding about which foods to avoid, which to monitor and which to eat most frequently. As discussed in the previous article our goal in terms of losing body fat is to maintain a constant moderate blood sugar level so that insulin is slowly released in smaller quantities making it easier to clear the insulin from the blood stream so that our body can return to burning fat. We will first be discussing naturally occurring sugars followed by processed sugars, how they differ and why they cause us to gain fat.
There are 4 primary types of sugars that occur naturally in our food;
Glucose - is found in all carbohydrates, glucose is one sugar molecule that all carbohydrates will break down into and is the bodies most preferred source of energy.
Lactose - Lactose is made up of two sugars, Glucose + Galactose these sugars are broken apart in the body and are found in milk and milk products.
Sucrose - sucrose is like Lactose in the sense that it is made up of two sugars also; 50% Glucose and 50% Fructose. It is found naturally in fruits, sugar cane and sugar beets. It makes up only 10% of the sugar in sugar cane but is refined into its purest form which we know commonly as sugar.
Fructose - fructose is just one sugar like glucose however unlike glucose which is found everywhere in nature, fructose was once very rare being found only in tree and vine fruits, honey and some rood vegetables. Fructose is the sugar that makes food sweet.
Our bodies evolved to run on glucose, it is after all the bodies preferred source of energy. Vegetables, grains and milk (lactose) all break down into glucose and if we are active this glucose is stored in our carbohydrate tank as discussed in part 1 or if we indulge too much get stored as fat. Fructose is metabolised differently to glucose as it was a very uncommon sugar during our evolution and the body does not cope very well digesting it. Sucrose or table sugar splits in the digestive system into fructose and glucose. This is a very important point to understand that our bodies are not good at taking in large quantities of fructose yet it has become a major constituent of processed food in the form of syrups, agave, coconut sugar, palm sugar and rice malt syrup. When our bodies break down these processed sugars they are split into glucose and fructose. Both sugars are absorbed through the digestive system and into the blood where they head to the liver for processing, the liver accepts glucose and knows exactly what to do with it because as mentioned earlier we evolved to handle it. The Liver also processes the fructose and is able to turn a small amount of it into glucose for when we run out after a marathon or a very long sleep. However if our glucose is topped up (usually it is) the liver turns all excess fructose directly into fat. Think of the liver as a warehouse, on one end of the warehouse glucose comes in and is sorted quickly and efficiently, the workers there have been dealing with glucose for a long time and know what needs to be done, if there is energy that is required they send the glucose out back into the blood and if not they store it in the muscle or the warehouse itself (the liver). On the other side of the warehouse there are a couple of guys who handle fructose, they have never really had to deal with large amounts because it was quite rare, unfortunately nowadays through high intakes of fruit juices, soft drinks sugary foods ect. They are being inundated and have no idea what to do with all the fructose, they try and store it out the back but its full of glucose so they have no option but to return to sender and store the fructose as fat.
Fructose from fruit is ok in very moderate amounts, usually 1-2 servings per day. The Fructose we need to be wary of is the fructose in sucrose which we now know is what all processed sugar is made from. Fructose was out of the spotlight because it has no effect on insulin so it got a free pass however now it has come to light that it is indeed the most harmful of sugars if taken in high amounts.
Processed sugar = high sucrose = fructose = fat
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