How detrimental is alcohol to testosterone production?
Varies from person to person. If you're not an aspiring bodybuilder and as long as you don't binge drink multiple times a week, you don't have anything to worry about.
This guy clearly drank himself retarded with his puppet show - YouTube- Alcohol and Bodybuilding - but he talks about the negative effects of alcohol on bb-ing and is fairly accurate.
Back.... for real this time
He's way off base to assume that the body works as a closed system and that drinking a beer a day will add on 15lbs of fat a year.
The REAL Effects of Alcohol on Your Body
Many of us associate the effects of alcohol on the body with the heart, lungs, liver, brain, memory, etc. Furthermore, if asked about effects of drinking alcohol in terms of our fitness goals, most people will let you know about the infamous beer belly.
You know what I’m talking about right?
Drink too much and you end up storing too many calories as fat.
Many people will choose low calorie alcohol drinks or low carb alcoholic beverages in an attempt to avoid the fat storage issue. They feel that by making this choice the only bad effects of alcohol – increased fat storage – will be minimized.
But what you didn’t know is that only about 5% of the calories from alcohol are stored as fat! 
Then it hit me as it should hit you right about now…
The effects of alcohol on the body are far more damaging than can be predicted by the number of empty calories in some alcoholic beverage.
The truth is…
1- Alcohol really affects the amount of fat your body can and will burn for energy!
In a study done by the American Journal of Clinical Research  they concluded that just a mere 24g of alcohol consumption showed whole-body lipid oxidation ( the rate at which your body burns fat) decreased by a whopping 73%!
When alcohol goes thru the liver, the by-product is called Acetate. It would appear that acetate puts the proverbial brakes on fat burning.
Your body can use many types of fuel. Protein, carbohydrates and fat. In many cases, the fuel used is dictated by it’s availability.
Your body tends to use whatever you feed it for fuel right? As your acetate levels increase, your body burns more acetate as fuel.
What this means is…
Fat burning takes a back seat!
What it all boils down to is this…
a) You consume a couple of alcoholic drinks or more. b) Your liver metabolizes that into acetate. c) Your body uses the acetate for fat as fuel.
2- Increase in appetite
In another American Journal of Clinical Nutrition study, there was evidence to suggest that consumption of alcohol lead to an increase in appetite over that of any other carbohydrate type drink. 
Researchers over in the Research Department of Human Nutrition and Center for Advanced Food Studies in Denmark  concluded that consumption of alcoholic beverages, and wine in particular, may enhance total energy intake at a meal relative to a soft drink, when served with no restriction.
3- Decrease in Testosterone and an Increase in Cortisol
A study of 8 healthy male volunteers observed that after drinking alcohol, the effects of a significant decrease in testosterone and an increase in cortisol (a muscle destroying hormone) lasted up to 24 hours! 
The only real question to ask yourself is this…
If you are serious about building muscle and burning fat, you want all the free testosterone levels you can get and you want to reduce cortisol in any way you can. That means go lite on the drinking because it does affect your hormones.
Is that the effects were even worse if you exercise before drinking.  This means that if you are going out and will be drinking more than a small amount of alcohol, you might as well skip the gym.
Not shocking is a study done by the Department of Radiology, Sahlgrenska Hospital, Goteborg, Sweden  that determined increased waist to hip ratio of alcoholics may include not only changes in adipose tissue, but also in muscle tissue distribution.
In layman’s terms.. that means more fat around the waist and less overall muscle mass.
4- Decrease in vitamin and mineral absorption
When you consume large quantities of alcohol, your liver is busy converting the alcohol to acetate and any vitamins and minerals that it might process are taken up by the detoxification process.
Alcohol interferes with the metabolism of most vitamins, and with the absorption of many nutrients. Alcohol stimulates both urinary calcium and magnesium excretion. 
This just means that you’ll get less of a benefit from the “healthy” meal you may be consuming.
Food in the stomach will compete with ethanol for absorption into the blood stream. It is well known that alcohol competes and influences the processing of nutrients in the body. 
5- Decrease in protein synthesis of type II fibers
This means the actual building of muscle is slowed down by 20%+ or more. This included a 35% decrease in muscle insulin-like growth factor-I (GF-I). 
A common side effect of alcohol is dehydration. Alcohol is a diuretic. Drinks containing 4% alcohol tend to delay the recovery process. 
Considering how important water is to muscle building and general health, it’s clear that dehydration can put a damper on your progress. After alcohol consumption the first thing you might want to do is drink coffee. But that’s a diuretic as well. How to avoid dehydration? Drink more water.
Alcohol consumption, especially at the times when you would normally sleep, can have effects on the quality of sleep. Clearly high quality sleep is extremely important to the rebuilding and growth process of muscle. Without proper rest and recovery, your gains will be affected.
Alcohol consumption can induce sleep disorders by disrupting the sequence and duration of sleep states and by altering total sleep time as well as the time required to fall asleep.
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