Drinking beer will cause gain of weight in the following way:

• Calories from alcohol.
• Increased appetite and hence consumption of more calories than normal.

Unless you are fond of drinking beer there are no rational reasons to consume beer for weight gain because of the following disadvantages:

• No nutritional value of the calories consumed.
• Weight gain in the form of fat accumulation.
• Lowered mental faculties till the time the effect of alcohol lasts.

To gain weight the best method is to:

• Increase protein intake to 1.5 to 2 gm per Kg of body weight per day.
• Increase strength building exercises to increase muscle mass rather than fat.
• Improve consumption of Calcium and Vitamin D (often Indian urban population has these deficiencies, particularly females) along with strength building exercises to improve bone density.

The muscle mass gain expectation should be gradual because the best results could be like:

• 1 kg in 2 months for males.
• 1 kg in 4 months for females.