Alcohol can add hundreds of calories to your daily intake, which can make the difference between weight loss, maintaining your current weight, or gaining weight. A single glass of beer or wine can contain at least 100 calories. Having a few drinks 3-4 nights a week could be adding 1,000 unforeseen calories to your diet. Alcohol also acts as an appetite stimulant, and can lead you to eat or crave foods that are not within with your weight-loss plan. If you are dieting or are simply having trouble getting rid of that last little bit of fat, keep your alcohol intake to a minimum.
source : health-fitness-tips.com
