To increase body weight in 30 days, you can follow these guidelines:

 Caloric Surplus: Consume more calories than your body burns. Use a calorie calculator to determine your needs and aim for an additional 500 calories per day.Protein Intake: Increase your protein intake to support muscle growth. Aim for about 1.6 to 2.2 grams of protein per kilogram of body weight.Strength Training: Engage in resistance training exercises to build muscle. Focus on compound exercises like squats, deadlifts, and bench presses.Frequent Meals: Eat 5-6 smaller meals throughout the day to maintain a steady intake of nutrients.Healthy Fats and Carbs: Incorporate healthy fats like nuts, avocados, and olive oil, and choose complex carbs like whole grains, vegetables, and fruits.Stay Hydrated: Drink plenty of water to stay hydrated and support overall bodily functions.Adequate Sleep: Ensure you get 7-9 hours of sleep per night to allow your body to recover and build muscle.Consistency: Stick to your plan and track your progress to make necessary adjustments.If you have any specific dietary restrictions or health conditions, it's advisable to consult a healthcare professional or a dietitian.