Change your mug color– This is a somewhat obscure suggestion, but a year or so ago a small study concluded that mug color could have an impact on how we taste our coffee. Specifically, using a white mug instead of a clear mug can make you perceive a coffee as more bitter and less sweet. If you regularly drink coffee out of a white mug, try changing it up and using a clear mug instead.
A shot or small portion of unsweetened coffee, now usually made either using an espresso machine or a moka pot, but traditionally made using a cloth drip, usually served in cups made for the purpose, called "tazitas de pocillo." It is widely drunk in Latin America, usually as an afternoon or after-dinner coffee. The defining feature is the size, usually half to a quarter the size of the usual ~8 US fluid ounces (240 ml) coffee cups. There are a number of small-sized drinks that use tazitas de pocillo, including such sweetened varieties as café cubano and café cortado, but these are usually not called a pocillo; rather, the Spanish diminutive suffix "-ito" is usually added to the name of the drink wanted in a pocillo size cup. For example, a pocillo-sized cortado is usually called a cortadito.
Caffeine is a natural stimulant that works in your brain by blocking the effects of adenosine, an inhibitory neurotransmitter  . This increases neuronal firing in the brain and releases other neurotransmitters like norepinephrine and dopamine which improves mood, reduces stress, increases vigilance and reaction time and general brain function  .
So I’m doing Keto and intermittent fasting so I’m trying to make the switch. I’ve gone to a Guatamalian lightly freshly roasted coffee; burr ground by hand just before I pour the water over the grounds and wait 45 sec to let it bloom; then pouring the rest of the water through it. I’m still finding it too bitter. I used 6 tablespoons for ~ 3, 8 oz cups. Should I try and adjust my grind, or the amount of coffee I add to the water to try and tamp down the strong bitter taste?
I don’t have a problem with people adding things to their coffee (my wife enjoys her coffee with cream and minimal disapproving head shakes from me) but I do think black coffee has its merits. It is my opinion that the vast majority of coffee additives are remnants from the first wave coffee notion that coffee is vile, caffeine is good and adding things to coffee makes it tolerable.
Cold brew coffee originated in Japan, where it has been a traditional method of coffee brewing for centuries. Slow-drip cold brew, also known as Kyoto-style, or as Dutch coffee in East Asia (after the name of coffee essences brought to Asia by the Dutch), refers to a process in which water is dripped through coffee grounds at room temperature over the course of many hours. Cold brew can be infused with nitrogen to make nitro cold brew coffee.