Buy large-sized sweat or elastic waist pants or skirts with wide elastic or whatever size you need. Choose pants or items that have the least sewing through the elastic that you can find. Not that it hurts the elastic, just takes more time to get it out.
Take seam ripper and dislodge your elastic. Considering it cost me $2.59 to buy elastic for the last pair of pants I made, getting pants for $1 or less would be totally worth the about 20 minutes it took me to take the elastic out. And if you can cram as many items in a sack as I can on dollar day, my elastic only cost me 2.5 cents and time.
Don't throw away old sweats until you take out and save the elastic! I know I won't be doing that anymore.