Velcro will hold very well on pants. Make sure to use the sew in kind (it's a little softer), also make sure to if you think you should only use a small amount - add a little more. I found with my dad he would see himself as one size and I would see him differently. If you you a little longer strips of Velcro, the pants can be pulled tighter or let out a little (after eating). The other reason I made the strip a little longer, was if the Velcro came undone for some reason. It would have a chance to re-hook it's self. On some of my dads work pants (around the house and yard - he didn't want me going to any trouble with work pants), I used the larger black elastic hair bands (the covered ones on the button hole side - you can adjust the loop so your dad will not have any trouble hooking it and to un-hook he only has to pull out with the button hole side). Good luck