A couple of years back, I gave up coffee because I felt it was causing me to have severe insomnia and significant anxiety. At the time, I was a carnivore and was often fasting. After doing some research, I did find plenty of positive information about coffee but also some negative. Since changing my diet, I have experienced some new things and decided to dig again into this topic which always seems to be controversial, much like carbohydrates.
In my personal experience, after having changed the way I drink coffee, it no longer affects me in that way. I always consume coffee with food and plenty of carbohydrates, usually in the form of fruit. In this case, I have no anxiety and no sleep issues.
How Coffee Helps
Coffee has some unique benefits that can actually really improve digestion and liver function. Its bitter components can stimulate bile production from the liver and help move toxins out of it. For the liver, caffeine can also be beneficial by reducing liver enzymes and may even affect alcohol-induced cirrhosis. Caffeine can stop the production of free radicals and have an anti-aging effect on the body’s tissues. Several studies demonstrate a reduced risk of breast cancer by suppressing and shrinking tumors. http://raypeat.com/articles/articles/caffeine.shtml
Coffee may even improve your gut microbiota. In one study, high caffeine consumers had high levels of the bacterial genera Faecalibacterium and Roseburia but low levels of Erysipelatoclostridium — a “potentially harmful” bacterial genus. https://www.medicalnewstoday.com/articles/326845#The-effects-of-coffee-on-the-gut
Another thing people are concerned with is that coffee may leach minerals from the body. There is no evidence of this, and in fact, the coffee itself contains a good amount of minerals. Drinking coffee does not cause dehydration either; even though there is a slight diuretic effect, it is not enough to negate the amount of liquid consumed in the drink itself. https://www.coffeeandhealth.org/topic-overview/nutrition-information/
How is coffee hurtful?
If you consume coffee on an empty stomach or follow a deficient carbohydrate diet, you may experience high-stress hormones. This is because caffeine mobilizes glucose, and if none is present in the diet, the body will turn to the liver to make it through gluconeogenesis. This process further increases the stress hormones. This may be felt by increased stress hormones and insomnia (my experience exactly).
For some people, coffee can irritate the stomach. However, I have found that different brands affect the gut differently, which may be related to chemicals or mold on the coffee.
If you love coffee and want to try drinking it, I highly recommend changing how you eat in conjunction with the coffee. The old approach of fasted and caffeinated workouts may give you an intense high but also an intense low and could be very stressful on the body. Higher stress hormones can in turn increase blood glucose and inflammation.