Coffee

I don't think it is a big deal to have your one, perhaps two delicious cups a day. There are even many health benefits that have been studied, and coffee drinking is associated with longevity. No need for guilt for such an enjoyable drink!

However, for many people, drinking strong coffee on an empty stomach first thing in the morning may be a bit rough- on the stomach, and on the adrenals. Often when we get up in the morning, if we don't eat within an hour or so, adrenalin will kick in to maintain steady blood sugar. 

Adding coffee (caffeine) to that, especially black and sugar-free coffee, strongly stimulates the adrenals. While that may make us feel more ready for the day, it's not so good if we are already having issues with chronic stress or exhaustion.

One way to buffer this is to have your coffee milky with sugar. This helps to balance the adrenalin effect. Sugar calms adrenalin. The fat and calcium in milk also help slow down the absorption of caffeine. 

The other way, which is what I recommend especially if you already have a lot of stress in your life or your adrenals are chronically activated, is to have your morning coffee with or after breakfast. The food will help balance your blood sugar (especially a balanced breakfast with protein and carbs) and you won't get that strong adrenalin spike but you do get a more gentle uplifting stimulant effect, along with the health benefits. I also recommend some simple carbs such as honey or fruit with breakfast, along with some protein, to support the adrenals. 

If you would like to read more about the benefits of coffee, here is a good article: http://raypeat.com/articles/articles/caffeine.shtml