Most people report a very good success ratio by cutting down caffeine intake at the rate of 1/2 cup of coffee a day. This is known as Caffeine Fading. Alternatively you might try reducing coffee intake in discrete steps of two-five cups of coffee less per week (depending on how high is your initial intake). If you are drinking more than 10 cups of coffee a day, you should seriously consider cutting down. While your tolerance to your caffeine levels will go up, the rate at which your body metabolizes caffeine doesn’t change significantly, and you can end up with high levels of caffeine around bed time. You should avoid trying to find out how to get caffeine out of your system by avoiding large quantities in the first place – here we’ll show you how.
Tapering your Coffee Consumption
The best way to proceed is to consume caffeine regularly for a week, while keeping a precise log of the times and amounts of caffeine intake (remember that chocolate, tea, soda beverages and many headache pills contain caffeine as well as coffee). At the end of the week proceed to reduce your coffee intake at the rate recommended above.
Remember to have substitutes available for drinking: if you are not going to have a hot cup of coffee at your 10 minute break, you might consider having hot chocolate or herbal tea, but NOT decaf, since decaf has also been shown to be addictive. This should take you through the works without much problem.
Quitting Cold Turkey
Some other people quit cold turkey. Withdrawal symptoms are quite nasty this way (see section below) but they can usually be countered with lots of sleep and exercise. Many people report being able to stop drinking caffeine almost cold-turkey while on holidays on the beach. If quitting cold turkey is proving too hard even in the beach, drinking a coke might help.
Light Roast vs. Dark Roast
There’s a myth floating around that light roasts contain more caffeine than darker roasts, and that perhaps you can reduce your caffeine intake by drinking a dark roast. There’s only minimal truth to this – roughly 5% caffeine is lost going from a light roast to a dark roast, not enough to be a serious solution. There’s also no relation between coffee’s taste and caffeine levels. A much better solution is to create your own 50/50 blend of regular coffee and decaf – letting you enjoy all the flavor of coffee with only half the caffeine.
Here’s another source analyzing caffeine (plus chlorogenic acid) content by roasting (and brewing) method: http://pubs.rsc.org/en/content/articlehtml/2014/fo/c4fo00290c