Simple Carbohydrates And Their Effect on Body Fat
Though the glycemic index categorizes most fruits as low GI, as you will see, the simple sugar found in fruits called fructose is metabolized differently than the sugars from starches. To understand how the process differs, first let’s see how the body uses glucose.
If blood glucose levels are low, the body uses the glucose it gets from foods and burns it immediately for energy. This is one of the reasons why after a workout, the body utilizes carbohydrates so efficiently. Now, assuming that there is no immediate need for energy, glucose is then into glycogen and stored in the liver or the muscles. The liver can hold roughly 100 grams of glycogen but the muscles, depending on how muscular you are, may store between 200-400 grams. The key point to remember here however is the following: The glycogen from muscles can only supply energy to the muscles when they are contracting (so muscle glycogen gets depleted badly during a weight training workout). Liver glycogen however can supply energy to the entire body. It is key to remember this in order to understand how fructose does not help with fat loss.
The way that the body gets fat with an excess of carbohydrates is that if all of the glycogen stores in the body are full, then the extra glucose is converted to fat by the liver and stored as adipose tissue (bodyfat), probably in your buns and thighs or around your waist.
Now that you understand how glucose is used and how fat can be stored in situations where all glycogen levels are full, lets go back to the fruits. What happens with fructose is that the muscles do not have the enzyme required to turn fructose into glycogen. The liver does so fructose replenishes the liver. It does not take much to replenish a liver of glycogen as it can hold around 100 grams only. Therefore, if you overdo the fruits, you will fill up your liver glycogen and this causes the body to release an enzyme called phosphofructokinase signaling the body that glycogen stores are full. Since the liver has to supply energy for the whole body, the body uses its glycogen stores as the fuel gauge. When the tank is full, so to speak, that is when any extra fuel gets stored away. Because of this, we suggest that fruits are limited and even eliminated if on an aggressive fat loss diet. By the way, if you are wondering why most fruits can be so low GI and still cause so much damage is because fructose leaves the liver as fat and fat does not raise insulin levels. Bummer!
Carbohydrate Consumption Recommendations
It is recommended that you eat mainly medium to low (55 or less GI) to medium (65 or less GI) glycemic complex carbs throughout the day, as they are responsible for creating consistent energy levels for peak performance and daily functions.
If you must eat fruits, minimize your consumption to two servings per day at times where some of your liver glycogen has been depleted. The best times are the morning with breakfast and right after a workout. This will help to speed up the recuperation time and aid in the production of lean muscle tissue. Ingesting simple carbs throughout the day is not recommended as if your liver glycogen is full, then you will risk storing body fat.
About The Author
, About.com's Bodybuilding Guide and ISSA Certified Fitness Trainer, is a nationally-known best-selling author of over 8 books on bodybuilding, weight loss and fitness, including "The Body Sculpting Bible for Men", "The Body Sculpting Bible for Women", "The Hardgainer's Bodybuilding Handbook", and his successful, self published e-book, "Body Re-Engineering". Hugo is also a national level NPC natural bodybuilding champion. Learn more about Hugo Rivera