INSTANT OATMEAL

instant oats have been chopped up more, or more broken down farther, or more refined, which makes it cook faster all of this is basically like its been prechewed. this makes it digest faster which basically raises the glycemic index and will possibly spike insulin. although i dont think with oats that the quick one minute oats that are plain (not the flavored stuff) are very high on the glycemic index anyway,they are just higher then the old fassion oats. also keep in mind that there are times when the higher gycemic stuff would be the preferred choice like in the morning or after a workout

Stick with the old fashioned, plus IMO they taste better

Slow cook or steel cut oats are the way to go. Like Vic said, the instant oats are okay in/around your post-workout meal (because they have a higher glycemic index); less-processed oats are better just about every other time of the day.