Discover the most important concepts for weight gain and keeping it on.

Hardgainers typically find it difficult getting enough calories to gain weight and build muscle. The secret to consuming enough calories is to choose calorie dense foods.
Fibrous carbohydrates and vegetables such as lettuce, asparagus, cucumber, and broccoli are very low calorie foods. This is because these vegetables are high in fiber and your body has a hard time absorbing the caloric content of fiber. These types of vegetables also have a high water content.
So now let’s look at some “calorie dense” foods which will help pack on the pounds. Leave the vegetables in the pantry if you want to gain weight, and replace them with simple carbohydrates such as fruits which have a higher calorie density. This is because simple carbs are more concentrated and they contain less fiber. 
Complex carbohydrates (starches) such as whole grains, pasta, cereals, beans, potatoes and rice also have higher calorie densities than fibrous carbs. A typical serving of pasta contains about 800-1000 calories. Pasta and other complex carbs are great foods for gaining weight.
Now that you know what carbs to eat, let’s talk about fat. There is a common misconception that all fats are bad for you and they should be removed from your diet. This is untrue, there are good and bad fats. Fats have a major impact on the calorie content of foods, so they are an important consideration. Just keep in mind that fat should consist of about 15-25% of your total calories. You want to be getting most of you calories from carbohydrates and protein.
In small amounts, unsaturated, “healthy” fats are not only good for you, but they can help you gain weight more quickly. Just one tablespoon of flaxseed oil and two tablespoons of peanut butter would add nearly 500 calories to your daily diet and you’d hardly notice that any extra food was added.
In addition, you can supplement your healthy diet with protein supplements. It is often difficult to eat enough protein each day from normal foods, so supplementing with a  weight gain suplement such as a soy or whey protein shake can help increase overall caloric intake. You want to make sure the weight gain supplement is a good mix of both protein and carbs and doesn’t contain too much sugar.

Healthy fat substitutes that help your muscle development

Healthy fat sources include nuts, egg yolks, flax seed, fatty fish such as salmon, olive and other plant-based oils (but only if not used in cooking). Animal and poultry fats are also ok in moderation.
Avoid processed fats such as found in most salad dressings and sweets. Also avoid cooking methods that use significant amounts of oils at high temperatures. Healthies ways of cooking vegetables, meats and fish are grilling, broiling, steaming, and others that do not require heating of oils.

Cook with olive oil or flax seed. Extra virgin olive oil is a healthy base for sauteing veggies or a simple salad dressing. Flax seed can be used as a fat substitute in baking recipes or mixed in with yogurt or oatmeal. It also is a source of protein, fiber, and even omega-3.

If eating out, consider Mexican food. Avocados provide healthy fats, and are quite filling. Guacamole adds tomatoes to the mix, which also provide lycopene. Red meat and black beans are a good protein option, but avoid white flour chips and tortillas. Dairy products provide many of the essential amino acids for muscle gain, but cheese also adds a significant amount of fat to your diet, so eat in moderation.