What is a way to gain weight with a fast metabolism?

If healthy, then...: Eat more healthy calories (snacks and meals) to gain weight. Choosing foods with protein and "good" fats and oils. Avoid excess amounts of simple starches and sugars. To increase muscle mass, one has to work out against resistance (with weights). This exercise will increase daily calorie needs, so one must eat more of the healthy, balanced diet he should already be on.

Eat healthy foods: high in calories. Eat 6 meals /day. Work on strength training to build large muscle groups. Work out w heavier weights w fewer repetitions. Sleep at least 8 to 9 hrs/night. Hydrate well w water. Foods to help w weight gain: almonds, cashews, pecans, sunflower seeds, flax seeds, walnuts, hummus, avocados, granola, trail mix, dried fruits, protein shakes & bars, lean meats, poultry, fish, smoothies