Presumably you already have a good idea that alcohol is bad for you and negatively affects your fitness and health. I'd also expect you to have an idea of its long-term effects such as linking to cancers, obesity and other such negative conditions/illnesses. So what I'm going to focus on is the finer details that relate it to fitness, predominantly weight lifting and weight loss. Be prepared to be surprised.
Alcohol and the beer belly
Ever wondered where the beer belly look comes from? There is a certain fat in your stomach called brown fat and this particular cell absorbs 6 x more calories from alcohol than other areas of the body. This is why you see many people who have a large stomach yet have relatively slim arms and legs. Drinking or supplementing with green tea is a proven way of increasing your metabolism and reducing fat found on the abdomen region.
Alcohol and the fat loss process
Surprisingly there is evidence that alcohol can stop the fat burning process for up to two weeks. Alcohol contains 7 kcal per gram of it, combine that with sugary mixers and you can easily be hitting 300/400 kcal per drink. It is certainly not recommended for those looking to lose weight especially in the stomach region.
Alcohol and sleep
Some people sleep better with alcohol but for most they struggle. This is because it causes a secretion of glutamine into your system which is a stimulant; hence terrible sleeps and having to suffer the hangover that little bit more. Quality sleep helps to secrete growth hormone; with a limited secretion of growth hormone you will gain lesser amounts of muscle and burn less fat.
Alcohol and testosterone
Testosterone is a vital hormone. It blocks cortisol and initiates protein synthesis, the act of building muscle from dietary protein. Alcohol lowers your testosterone levels whilst intoxicated and whilst it is in your system so I really wouldn't recommend drinking after you have trained in the gym.
I hope this give you an insight into alcohol and why it is very poor for those looking to achieve their nutritional and fitness goals. Some prefer to cut alcohol out of their diet completely but personally I believe in moderation, cutting it down and drinking only on occasions. You know your body better than others so you decide on this one. Another surprising fact is alcohol and smoking are amongst the worst of the banned drugs for fitness and health, that includes heroin and cocaine but I wouldn't really advise taking them either