input: [Recommendation] Keep your eye on the GI [Why] 
output: The glycemic index is a measure of a food's ability to raise blood sugar levels. Before exercise, low-GI foods can be beneficial, while high-GI foods can quickly restore sugar stores after exercise. The glycemic index (GI) is a measure of the ability of a food to raise blood sugar levels after it is eaten. Attention to the GI of carbohydrate sources may be helpful for increasing sports performance. Within one hour before exercise, consuming low GI carbohydrates (such as most fruits, pasta, legumes, or rice) provides carbohydrate without triggering a rapid rise in insulin that could result in hypoglycemia and prevent release of energy sources from fat cells.48 Some controlled studies of cycling endurance have found that eating a pre-exercise meal of low-GI foods (lentils, rolled oats, or a combination of low GI foods) is more effective than consuming high-GI foods (potatoes, puffed rice, or a combination of high GI foods),49 , 50 , 51 but most studies have found no significant advantage of low GI foods or fructose (a low-GI sugar) compared with other carbohydrate sources in a pre-exercise meal. 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 After exercise, on the other hand, high-GI foods and beverages may be most helpful for quickly restoring depleted glycogen stores.60