Ive had success with eating a lot of peanut butter and whole milk. I was gaining 3-4 pounds every week without supplements. After eating 3 cups of peanut butter a day my body started getting used to it and compensated for the extra food intake. My metabolism sped up and I didn't gain weight for 5-6 weeks. I got on whey protein and even though it doesn't give the fastest results it will put on muscle weight.