said by LazMan:A alcoholic, used to drinking a fifth of vodka a day, for instance - going cold turkey could cause DT's - tremors, hallucinations, heart palpitations, and possibly coma/death...
... where did the OP say he was an alcoholic or a drug addict?
We're talking about lifestyle changes not heroin. In almost every instance a person making sudden positive lifestyle changes they will go over just fine and suggesting they can't are simply more excuses the person doesn't need, especially from others.
If a person wakes up one morning and says, "I'm going to start eating healthy. I'm going to stop drinking coffee, I'm going to cut down on salt, and I'm going to start exercising", everyone should be doing everything in their power to encourage level of motivation and not discourage it.
Obviously if a person experiences the worst symptoms of caffeine withdrawal, like flu-like symptoms, they should wean themselves but if there are no serious negative symptoms, which qualifies the majority of experiences in the 50+ studies on caffeine addiction, they should steamroll ahead.
zacron sounds like he has the motivation right now and it's an uphill battle so we should be doing everything we can to positively encourage him to get through this.
Everyone I know who made a similar lifestyle change to zacron did it just the same with stellar results, immediately quit everything 'bad' and go for gold and they all noticed positive changes within a few weeks.