Diet and nutrition is the single most important factor in wanting to gain weight. You can do all the weight training you want, but if you are not feeding your body the necessary food and nutrients it requires for maintenance and growth, then it will all be a waste of time, not to mention unhealthy. Knowing what to eat to gain weight is essential for putting on the pounds. In a nutshell, your weight gaining diet should include high protein foods, high carbohydrate foods and healthy fats. Diet and nutrition is the single most important factor in wanting to gain weight. You can do all the weight training you want, but if you are not feeding your body the necessary food and nutrients it requires for maintenance and growth, then it will all be a waste of time, not to mention unhealthy. Knowing what to eat to gain weight is essential for putting on the pounds. In a nutshell, your weight gaining diet should include high protein foods, high carbohydrate foods and healthy fats. Either way, you should choose foods that are nutrient-dense instead of settling for high-calorie junk foods. Nutrient-dense foods include fruits, vegetables and whole grains. Foods that are both energy- and nutrient-dense include legumes, nuts, seeds, olives, and avocados. You may also want to increase your consumption of dairy products, meats, seafood and poultry. Use seasoning blends, herbs and spices to add flavor and aroma. Exercise regularly for healthy weight gain. Some thin people think that exercise is not good for them. This is not true, it keeps the metabolism high. Remember that eating alone is not sufficient. You don’t want to gain fat but lean mass, so exercise is important. Resistance training exercises will help to increase your muscle mass, which in turn will increase metabolism. Learn to distinguish between weight gaining exercises and weight loss exercises. Note that if you do not get enough amino acids during exercise, the existing muscle may break down. Amino acids come from protein rich foods.