If you struggle to put on size then mix regular workouts with a proper weight gain diet if you want the best and quickest results . You cannot expect good results if your just working out but not eating the right diet.The reason for this is because while a workout will stimulate your body, you still need a proper diet to feed and grow your muscles. It is essential that you understand that your diet choices are vital for the reaching your muscle building goals. 

The  food tips listed below will help you create a good weight gain diet: 

1.Eat plenty of Protein – A staple body building diet includes various sources of protein. Proteins contain amino acids which are the building blocks of your body.  Without amino acids, you would not be able to grow, repair or maintain muscle tissue, which is why protein rich foods are so important. Foods that are classified as good sources of protein include beef, chicken breast turkey, salmon, tuna and eggs . When choosing meats as your choice for protein be sure to remove any excess fat. For optimal muscle building try and aim for between a protein intake of 20%-30% of your total daily calories. 

2. Keep eating Carbohydrates-Contrary to some opinion carbohydrates ARE a vital factor of the muscle building diet. A number of bodybuilders seem to think that the only nutrient responsible for muscle growth is protein. Protein may be primarily responsible for the repair and rebuilding of muscle tissue but it can only accomplish this job when the other  nutrients are present in the diet. If carbs are scarce in the diet the body will look to convert protein into energy, a process you don’t want to happen when hoping to build muscle. Only through a diet that includes enough carb intake can a body achieve its optimal muscle building potential. For the best results when eating carbs (ie you build muscle without gaining fat) it is important to know which type of carbohydrate to consume . Carbs known as complex types are the preferred foods to eat as they are broken down more slowly in the body resulting in a release of energy that last for longer. The benefit of this can be seen with stronger workouts, fast recovery and a more efficient muscle building process. ,For complex carb foods look at oatmeal, vegetables wholegrain breads, sweet potatoes and brown rice or pasta. A daily carbohydrate intake of 50%-60% of total calories is best for optimal muscle building. 

3. Include Healthy Fats– A small amount of the right fats in your daily diet are beneficial for health and assist the body to grow muscle and reduce fat more easily . This is because they help keep testosterone levels high that are vital for muscle growth and increases the rate of metabolic reactions in the body resulting in more fat being burned . Good sources of healthy fats are found in most types nuts, oily fish such as sardines and salmon, avocados and oils such as flaxseed and olive. A daily fat intake of 15%-25% of total calories is best for optimal muscle building. .

4. Invest in a quality Whey protein supplement–  In my opinion the only supplement worth taking when building muscle is a whey protein. Although you can get all your protein requirements from natural sources I feel that using a quality whey supplement in addition to natural protein food sources can be beneficial. Protein rich whey is easily absorbed and hence is an ideal body building food for using just after a workout when the body needs protein quickly.It is typically added to shakes and smoothies using either water, milk or fruit juices . Whey protein can be purchased from health food or body building shop and is a readily available protein. 

It follows then that the best weight gaining diet requires a balanced protein, carb and fat intake . You will experience muscle growth in a very short time if this is combined with an effective exercise progam.