Energy bars are food supplements containing high doses of carbohydrates (usually a mixture of different carbohydrates characterised by a different glycemic index) and a less abundant amount of fat and protein. The consumption of energy bars is recommended before or during physical activity to extend the workout's duration, or immediately after exercising, to promote energy recovery. The different carbohydrates that compose them would allow both to maintain constant blood sugar levels during prolonged physical activity (in particular, those with a low glycemic index) and to increase the energy available and favour the restoration of the body's resources (those with a high glycemic index).