The Science of Energy Gels

A sport fuel is most easily absorbed when it is isotonic. The word isotonic means that there is the same concentration of molecules in the fuel as in the blood.

Most Gels are made from maltodextrin (sometime called maltodextrose), which is a long molecule made up of linked glucose. Because maltodextrin has larger molecules, you can have a lot of it in an isotonic solution. Most Gels are close to isotonic without any significant dilution. Maltodextrin is isotonic at 150g (600 Calories)/16 oz or 9g/oz. Gels are typically 25g/1oz, requiring only an equal quantity of liquid to dilute. This can be achieved using by mixing the gel with saliva as it is consumed.

This makes gels very easily digested. A metric for how easily carbohydrates are digested is the Glycemic Index, which is how much the blood sugar rises when a food is digested compared with glucose. Maltodextrin has a glycemic index >100.

Note that there are some Gels that are not maltodextrin based, such as Clif Shots use brown rice syrup.