How can I tell if something is a fast-digesting carbohydrate?

The faster your body digests a carbohydrate, the faster your blood sugar will spike. Fiber helps slow digestion, so the more fiber a food has relative to its carbohydrate content, the slower-digesting a carbohydrate it will be, the more stable your blood sugar will stay and the less likely your body will be to store energy as fat. We’ve already identified lots of fast-digesting carbohydrates on the list of red foods on the Calibrate Food Triangle. You can also use the carb:fiber ratio to help separate out the slower-digesting carbs.