How can someone most easily gain weight fast, and what diet plans do you recommend?

Not fast.: Eat healthy high calorie foods. Eat 6 meals/day. Work on strength training to build your large muscle groups. Workout w heavier weights w fewer repetitions. Sleep at least 8 to 9 hrs/night. Hydrate well w water. Foods to help w healthy weight gain: almonds, cashews, pecans, sunflower seeds, flax seeds, walnuts, hummus, avocados, granola, trail mix, dried fruits, extra virgin olive oil, canola oil.