Although I titled this post ‘in defense of fructose” that is actually incorrect. I am not here to defend fructose but rather what people most associate fructose with. Fruit. There are many studies that state that any fructose the body cannot use is preferentially converted to fat. This has been the major reason why natural bodybuilders and anyone else who is trying to shed that last layer of fat off their six pack has been encouraged to avoid fruit. I think fruit is getting a bad rap here and people are assuming too much when they lay the blame for substandard fat loss on fruit consumption. In these studies very rarely (or maybe never, I could not find one) is fruit used as the source of fructose. More often than not it is high fructose corn syrup. Apples and pears are two of the highest fructose containing fruits. They have about 5-7g of fructose per 100g. High fructose corn syrup has anywhere from 55-90g per 100g.

Lets take a step back here and explain why excess fructose can lead to fat gain.Your body uses glycogen for fuel.What happens with fructose is that the muscles do not have the enzyme required to turn fructose into glycogen. The liver has this enzyme so fructose replenishes the liver. It does not take much to replenish a liver of glycogen as it can hold around 100 grams only. Any other carbohydrate you eat are turned into glucose and are either used immediately for energy if blood glucose levels are low or stored in the muscles, which can hold about 400g depending on the person, or liver to be used for energy later.

Ok still with me? Aright, so if the muscles and the liver are both full of glycogen and their is no immediate need for glucose, any additional fructose will be shuttled toward fat storage. Because the liver holds so much less than the muscles and only the liver can process fructose the jump is made that fructose will be converted to body fat easier than glucose.

Now here is my basic problem with the above scenario, which is absolutely true by the way. Anybody that is trying to get lean is going to be in a calorie deficit, or a least they should be. In order for any excess carbohydrate to be converted to fat there has to be just that, an excess. This does not happen in any properly designed diet I have ever seen. People usually need periodic “refeeds” of carbohydrate because these stores become so depleted over time.

If we take the general public the story is much different, but not because they are eating too much fruit. Nearly everything processed and packaged is loaded with high fructose corn syrup and other sugars. Put this type of diet with a low activity level that does not burn much energy (glucose) and you have a recipe for rapid fat gain.

The point I am trying to make here is we are not getting fat or not losing fat because we eat too much fruit. We eat too much period. The problem does not lie in overconsumption of natural food. When was the last time you saw someone sit down and eat half a box of apples? A Costco bag of chips and a big gulp is a whole lot more common.

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