When alcohol is consumed, it puts the brakes on fat breakdown. The processing of ingested alcohol takes precedence over the processing of proteins, fats or carbohydrates in the body. Alcohol suppresses fat oxidation or fat breakdown and weight-loss is all about fat breakdown. Simply put, if there is no fat oxidation then there will be no weight loss.
The type of food you eat when you drink alcohol is also likely to impact weight gain. Two beers and a plate of chicken wings is going to contribute more to weight gain than grilled chicken tenders and sauce on the side. Be careful of the type of beverage you choose. While a lite beer or a wine spritzer could have as little as 45 calories, a margarita or pina colada can contain more than 400 calories.