How long a particular food takes to digest depends primarily on its macronutrient makeup. Of the three macronutrients, carbohydrates digest the quickest, while fats are the slowest to digest. Pasta is primarily made up of carbohydrate with some protein and a trace amount of fat. Another component of judging the digestion speed of your pasta meal is what the pasta is made of.
Digestion of Carbs, Protein and Fat
Digestion is the process of breaking down food into small enough components that the nutrients can be absorbed through the intestinal wall into your bloodstream for use throughout your body. The rate at which carbs, protein and fats are digested has to do with their chemical makeup and where they are digested. Fats and proteins are more complex molecules than carbohydrates, which means they take longer for the body to break apart. Also, carbohydrate digestion begins in the mouth, when you take your first bite. Protein digestion begins in the stomach, and fat digestion doesn't begin until the food reaches the small intestine.
Factors in Food Transit Times
Another factor in how long your pasta takes to digest is what kind of carbs it's composed of. White pasta is made of refined flour that has had most of its fiber removed during processing. Fiber slows digestion, and without it, the carbohydrates are digested and absorbed into your bloodstream very quickly. Whole-grain pasta made from wheat, brown rice or quinoa, on the other hand, still retains its fiber and is digested more slowly. The other contents of your meal can affect transit time as well. If your pasta was covered with a high-fat sauce, for example, that can slow digestion. How much pasta you eat also affects transit time, with larger volumes of pasta taking longer to digest.
Actual Transit Time
According to the Colorado State University website, transit times will vary considerably among individuals. The variety of factors affecting digestion makes it impossible to provide a specific time for the digestion of pasta. Some conclusions can be drawn, however. In healthy adults, average transit times of food from the mouth is about 24 to 72 hours. If you eat a standard portion of white pasta, which is 1/2 cup, with a low-fat marinara sauce, you can expect transit time to be on the low end of that scale. A higher fiber pasta, a larger portion and components of your meal that are higher in fat and protein will increase transit time.
Pasta and Your Blood Sugar
As a carbohydrate food, pasta has the ability to raise your blood sugar. How quickly your pasta is digested and absorbed is what determines how much of an effect it will have on your levels. The glycemic index is a tool used to measure how quickly carbs are digested and absorbed and what effect they have on your blood sugar. The higher the number, the more quickly the carbs are digested and the more likely you are to experience fluctuations in energy and other negative effects of blood sugar spikes. Most pasta has a fairly low glycemic index, but whole-grain pasta is lower, with a GI of 37, compared to white pasta with a GI of 41.