A food with a low glycemic index (GI) is one that causes a slower, more gradual increase in blood sugar levels compared to high-GI foods. Low-GI foods, such as whole grains, legumes, and certain fruits and vegetables, are preferable for managing blood sugar and can aid in weight control. They provide sustained energy and can reduce the risk of developing insulin resistance and type 2 diabetes. Incorporating low-GI foods into the diet contributes to overall health and stable energy levels throughout the day.