Do it "Cold Turkey." I like this idea the LEAST.
The abrupt shift represented by this approach is a shock to your metabolism.
This might be also called the "Shoot First and Let God Sort Them Out" approach. It's impulsive.
But, for some people this works best. If you were able to quit smoking this way, without the benefit of a nicotine patch or gum, then maybe this will work for you.
One note: even if you take the time to Plan & Shop, as many do, or you even follow the full plan (recommended), at some point you will have to "take the plunge."
In the end, if you find Flour and Sugar to be a problem and want to move beyond them, you'll find that we all have to go "Cold Turkey" from Flour and Sugar at some point.