So we know that sugars are responsible for a lot of problems; obesity, diabetes, and overall inflammation and disease…..lovely. But where do we stand on fructose? Does the naturally occurring sugar found in fruits carry with it the same issues? Will fruit make you fat?
I think it’s important that we gain an understanding of how our bodies metabolise fructose before we give it the thumbs up or thumbs down.
When we consume carbohydrates, our bodies act to store them in one of two ways, either as muscle glycogen or liver glycogen. The source of the carbohydrates we eat will determine where that glycogen ends up being stored within the body.
Regular glucose from starches such as pasta and rice are stored as muscle glycogen, whereas fructose on the other hand is stored solely as liver glycogen. There is no crossover between the two. So glucose won’t replenish liver glycogen, and fructose won’t replenish muscle glycogen. Given that, the body has a lot more storage space for glucose, as there’s a lot of muscle tissue readily available to store all that energy. And as fructose is only processed within one organ, the liver, the bodies volume capacity for fruit/fructose is significantly less than that of starchy carbs.
Problems start to arise when our liver glycogen stores are full, and we continue to consume fructose. Due to the fact that our livers can only store a small amount of glycogen (2-3 glasses worth of orange juice), consuming fruits beyond a certain point will cause the excess to be changed directly into liver fat.
Overconsumption of fructose can increase DNL (process leading to fatty liver) five fold, and if you were to eat the caloric equivalent of glucose as fructose instead, you will increase liver fat by a massive 38% within only eight days. And fatty liver leads to insulin resistance. And these are issues that will manifest as long term chronic illnesses such as diabetes etc.
So it isn’t that fruit is bad for you, in fact, fruits are full of nutrients and vitamins. However, like most things, overconsumption can lead to problems. So enjoy eating your fruit, but remember that your liver can only metabolise so much before it begins to be stored as fat. So don’t go crazy!