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. [13]

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. [12]

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). [9]

6- Dehydration

A common side effect of alcohol is dehydration. Alcohol is a diuretic. Drinks containing 4% alcohol tend to delay the recovery process. [11]

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.

7- Sleep

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. [10]

8- The next day

A rather obvious conclusion but if you plan on drinking on a Friday night in excess then the leg workout you thought of doing on Saturday morning won't be top notch. It takes a bit to recover, your body to detoxify and for you mentally to be prepared to workout.

Not to mention you need energy for the workout ahead.

Sure you can hit the weights but my point is...

It's not going to be the best workout you've ever experienced.

At this point you might be totally discouraged to ever drink any alcohol again. But there's some good news.

Here's proof...

In the November 2004 issue of the International Journal of Obesity [7] they did a study on the effects of moderate consumption of white wine on weight loss.

Each group consumed 1500 calories. 150 calories came from white wine in one group and 150 calories from grape juice in another.

The conclusion?

An energy-restricted diet is effective in overweight and obese subjects used to drinking moderate amounts of alcohol. A diet with 10% of energy derived from white wine is as effective as an isocaloric diet with 10% of energy derived from grape juice.

It's simple: Moderation is the key! (with first place being abstinence as you already know).

In any event...

The effects of alcohol on your body when it comes to building muscle and burning fat are quite clear. It is a lot more than just some extra calories stored as fat. If you consume too much, it can derail your goals a lot longer after your head has hit the pillow and you've gone to sleep.

References:

1. Heikkonen, E., Ylikahri, R., Roine, R., Valimaki, M., Harkonen, M., & Salaspuro, M. (1996). The combined effect of alcohol and physical exercise on serum testosterone, luteinizing hormone, and cortisol in males. Alcoholism, Clinical and Experimental Research, 20, 711-716

2. Kvist, H., Hallgren, P., Jonsson, L., Pettersson, P., Sjoberg, C., Sjostrom, L., & Bjorntorp, P. (1993). Distribution of adipose tissue and muscle mass in alcoholic men. Metabolism, 42, 569-573

3. Raben A, Agerholm-Larsen L, Flint A, Holst JJ, Astrup A. (2003). Meals with similar energy densities but rich in protein, fat, carbohydrate, or alcohol have different effects on energy expenditure and substrate metabolism but not on appetite and energy intake. American Journal of Clinical Nutrition, 77, 91-100

4. Siler, S.Q., Neese, R.A., & Hellerstein, M.K. (1999). De novo lipogenesis, lipid kinetics, and whole-body lipid balances in humans after acute alcohol consumption. American Journal of Clinical Nutrition, 70, 928-936

5. Tremblay, A., & St-Pierre, S. (1996). The hyperphagic effect of a high-fat diet and alcohol intake persists after control for energy density. American Journal of Clinical Nutrition, 63, 479-482

6. Valimaki, M.J., Harkonen, M., Eriksson, C.J., & Ylikahri, R.H. (1984). Sex hormones and adrenocortical steroids in men acutely intoxicated with ethanol. Alcohol, 1, 89-93

7. Flechtner-Mors, M., Biesalski, H.K., Jenkinson, C.P., Adler, G., & Ditschuneit, H.H. (2004). Effects of moderate consumption of white wine on weight loss in overweight and obese subjects. International Journal of Obesity and Related Metabolic Disorders, 28, 1420-1426

8. Buemann, B., Toubro, S., & Astrup, A. (2002). The effect of wine or beer versus a carbonated soft drink, served at a meal, on ad libitum energy intake. International Journal of Obesity and Related Metabolic Disorders, 26, 1367-1372

9. Lang CH, Frost RA, Kumar V, Wu D, Vary TC. (2000). Inhibition of muscle protein synthesis by alcohol is associated with modulation of eIF2B and eIF4E, 3, 322-31

10. Alcohol Alert, National Institute on Alcohol Abuse and Alcoholism, No. 41 July. 1988

11. Shirreffs, Susan M., and Ronald J Maughan. 91997). Restoration of fluid balance after exercise-induced dehydration: effects of alcohol consumption, Journal of Applied Physiology, Vol. 83, No. 4, pp. 1152-1158

12. "Alcohol, chemistry and you," Kennesaw State University, chemcases.com, Aug. 2002

13. Dept. of Health and Human Services, Report to Congress, 1990

14. "Why alcohol calories are more important than you think," Christian Finn, TheFactsAboutFitness.com