What are some natural remedies to thicken up fine/thin hair?

Im deeply against animal testing, so im always very limited in what i can actually use. Nearly all the products that aren't tested on animals are very expensive and work great, or very cheap, but don't work at all. So i usually turn to natural home made remedies. But i can't find any natural remedies that work to thicken up my hair. So far i've tried extra virgin olive oil, honey +bio yogurt, and mashed banana + bio yogurt + olive oil (All made my hair feel lovely and look shiny and healthy but didn't plump up my hair).