Today NPR highlighted a recent study conducted by David Ludwig, MD of Children’s Hospital in Boston that illustrated the appetite-suppressing benefits of a well balanced low glycemic index (GI) diet. As one of the study’s participants explained, high GI carbs just did not sustain him and he was hungry soon after polishing off a large bowl of mashed potatoes. This is because high GI carbs (like mashed potatoes) are quickly digested in the gut. This causes first a surge of sugar to be released into the blood followed by a rapid drop in sugar levels from all the insulin the pancreas released in response to the mashed potatoes. This roller coaster results in hunger, low energy and causes the body to more readily store calories as fat.
Not all nutrition professionals look kindly on the concept of the glycemic index. As the dietitian who was interviewed for this segment mentioned, there are many variables that may impact on a food’s GI value: the ripeness of a fruit, the under- or overcooking of starches like pasta or rice, the presence or absence of other nutrients in the gut along with the carb (fat, protein, soluble fiber). Thanks to decades of valid GI testing by researchers in many parts of the world, we know these facts to be true. However, this is indeed how we eat. Our pasta at dinner tonight was cooked. The length of time it stayed in the water, the fat-protein-fiber content of the other foods on that same dish are factors that influenced the rate at which our gut is turning that pasta into glucose and releasing it into our blood supply. The glycemic index is telling us what the body already knows!