I know that a lot of people shy away from altering their own clothes, but it really isn't that difficult! If you have a sewing machine, or know one that you can borrow, it is fairly simple to take in the seams to make it a few inches smaller. As long as the pants or shirt have a straight seam, use a sewing gauge or ruler to pin and mark your desiered amount to take in. Say you are taking your pants in 1 inch all the way down, turn the pants inside out, measure pin, and sew! If you would feel more comfortable, use the marking pens to draw yourself a line to sew on.
And if you are off a bit on a couple of stitches, is it really going to matter? No one will inspect your seams! This is the best way that I have found to extend the life of my fat clothes!
By doing this, I can keep stashing money away for my skinny clothes!!!!