Does coffee make you fat? And only by listening to something like this, you may start laughing insanely, especially because black coffee contains no calories. But as you will see, it is not so funny, especially when it's based on science.
You may have read countless posts mentioning the positive benefits of the coffee or caffeine in the body and you may be reading this article with a question. But I have to mention something those articles certainly 'forgot' to mention.
Most of these articles are choosing studies about the positive benefits of the coffee. But the coffee used in these studies is real ground coffee and not the instant stuff supermarkets sold, where they have take the surplus of the good blends (the good stuff goes to the expensive market) and then they just mix the blend with chemicals [1, 2], chemicals that also are contained in the products of the large coffeehouses [3, 4]. These chemicals, among other things, are also needed to create the foam in the coffee.
And I am not referring to the natural bubbles on the top of the coffee (such as on the Turkish coffee) , but to the foam created from instant coffee.
Caffeine has not been created by nature to "wake you up", no matter if is evolved into a multi-bullion industry. Caffeine is found in varying amounts in the grains, leaves, and fruits of certain plants and naturally is being used as a pesticide to paralyze and kills certain insects.
And despite coffee is low in calories and has low glycemic index, coffee may cause diabetes, insulin resistance, but also it secretes cortisol, which in turn causes more problems. In general, coffee causes countless problems in the body and I will not mention every problem in this article. But if you want to learn more, I would suggest you read the book "Caffeine Blues: Wake Up to the Hidden Dangers of America's #1 Drug" [Amzn], or "The Truth About Caffeine" [Amzn].
Many years ago, I started had headaches while I was doing martial arts. My doctor told me that I had high blood pressure (hypertension) and I told him to let me first find out why I had hypertension, before try something else (I hate medicines). After changes to my lifestyle and nutrition, the numbers were still high. Until one morning I realized that the only thing I didn't change, was my coffee intake. So I reduced my coffee intake and guess what, in 2 days my numbers returned to normal. Health benefits my a$$.
Coffee contains mycotoxins
Studies has shown that almost all coffee beans are infected with mycotoxins [6, 7]. Mycotoxins are highly toxic substances produced by specific fungi and they grow in coffee beans. These mycotoxins are associated with many problems, such as cardiomyopathy , cancer , hypertension , kidney disease  and brain problems .
Coffee affects insulin
By drinking coffee, your body secretes insulin, because coffee increases blood sugar , although it has no calories. If you are on a keto diet, coffee (even black) will slow down your effects, due to insulin secretion, which in turn stops the production of ketones in the blood. I tried this personally (with Ketostix) and you can try it on your own.
Also, if you drink coffee after a meal (or with your meal), it will cause an excessive increase in insulin because coffee temporarily blocks insulin's action , so that glucose can not easily enter the cells. This process over time may potentially cause insulin resistance  and weight gain.
Coffee affects cholesterol
Coffee contains two anti-cancer substances cafestol and kahweol. The paradox of the hypothesis is that although these substances (diterpenes) have shown in animal studies that they have an anti-carcinogenic effect, they are the same diterpenes considered responsible for the increase in LDL-cholesterol and triglycerides [16, 17].
Coffee affects Cortisol
Coffee consumption increases cortisol levels , especially when consumed at times when cortisol increases naturally (eg in the morning). So experts recommend drinking coffee a few hours after you wake up .
Normally when we wake up, we take the energy we need from cortisol. Coffee consumption blocks this function and then we rely on coffee for energy, which is why we need more and more cups of coffee over time, and this results in an increase of the problems caused by coffee .
Coffee affects Your Gut
If you drink a lot of coffee first thing in the morning on a regular basis, may cause you gut problems. Drinking coffee, especially in the morning on an empty stomach, reduces the amount of stomach acid available for digestion later on.
H. pylori bacteria, the main bacteria responsible for ulcers, prefers highly acidic environments. Combine this with the way coffee weakens the protective barrier of the stomach – the mucosal layer — and the risk of damage and ulcers increases [24, 25, 26, 27, 28].
Drinking enough coffee may cause you acid reflux or heartburn, as coffee relaxes the esophageal sphincter — the 'tool' that closes the stomach when food is being swallowed and make sure it stays in there . Stomach acid that escapes irritates the tissue of the esophagus. Dysfunction of the esophageal sphincter causes gastroesophageal reflux, which causes heartburn and, if it happens often enough, can lead to gastroesophageal reflux disease, with damage of the esophageal mucosa [30, 31].
Coffee should be avoided by someone who is overweight and wants to lose weight or if you rely on coffee to get your energy. You should not be deceived by the lack of calories in coffee or the hype that has been created, coffee causes countless problems in the body, especially when it's being consumed in large quantities (over 2-3 coffees a day). And note that coffee from coffeehouses contains a large amount of caffeine, so a cup of coffee should not be measured as "one" coffee.