The glycemic index (GI) measures how quickly foods raise blood sugar levels. Foods with a high GI cause rapid spikes in glucose, which can lead to insulin resistance and increased cravings, impacting overall energy levels. Conversely, low-GI foods promote gradual increases in blood sugar, providing sustained energy and better appetite control. Understanding the GI can aid in dietary choices for those managing conditions like diabetes or weight control, essentially influencing overall health through diet management.