What is the best vitamin for getting fat

What are the vitamin needed to gain weight?
Omega 3 tablets once-twice daily can help gain weight
Yeast pills to increase appetite
Multi Vitamins and supplements
What are the ways to gain weight?
Weight gain can be achieved through:
    High caloric diet
    Increase the number of meals to 6
    Dairy products
    Avocado
    Meat, Chicken, Fish
    Add cheese or butter to the meals
  Avoid excessive effort
What causes low weight?
    Genetic
    Neurodegenerative disease
    Stress
    Hyperthyroidism
    Worms and intestinal parasites
    Malabsorption diseases
    Malnutrition