Here’s a question I’ve had for a long time for all you scientists out there…if I remember correctly from my high school nutrition class, it takes like 22 hours for you to digest food. So then how and why is it so important to get that post workout shake down within an hour? Isn’t your body using food from the day before during and after your workout?
I believe that it actually takes 22 hours for food too pass through your system. From anatomy/physiology classes, I seem to remember it only taking 3-4 hours for most proteins and carbs to be digested, the sugars were even faster. Most of this is absorbed while being digested.
The 22 hours is a complex process that sucks out most of the nutrients as well as vitamins from your food. Water and enzymes are added and removed by the process.
It is important to get the post-workout shake down quickly to cause an insulin “spike” (a sharp rise in insulin caused by a rise in blood sugar as well as by the properties of e.g. whey). This halts catabolism caused by the workout. In addition, the insulin causes the carbohydrates to be stored in the muscles as glycogen.