For some reason I have three or four pairs of jeans that are too big around the waist for me -- usually about a size (about an inch or so) too big. I don't know how this happened, maybe it's because I didn't want them to be too tight on the legs. But anyhow, I'm not a big fan of belts (at least belts that HAVE to be worn), so I decided to find a way to make them smaller without making them look stupid and painfully obvious.
This is how I did it (I'm sorry I don't have pictures of the process, just the finished product). This might be a little wordy but I want to be specific.
*You will need a needle capable of sewing denim. You also might want to use the same gold-brown thread denim-specific most jeans are sewed with. It’s a little heavier and blends in. I didn’t use it, and instead used a thinner thread of similar color, but later bought the denim thread at Jo Ann Fabrics.
1. Put on the jeans and pinch them or pin them to determine how much excess fabric you want to remove from the waistband. Mark the measurement anywhere on the waistband.
2. Take them off and measure how much you marked. You will be removing this fabric from the center of the back of the waistband, so re-mark it exactly in the center (that is, so that the center belt-loop is exactly in the center of the measurement.)
3. Now, remove the top connections of the three belt loops that occur on the back side of the pants (past the seams that run down the outside of the legs). This is so that you can remove the waistband. The TOP connections are removed because we want don’t want them to all run towards the back and be spaced funny.
**Also remove all the tags that might be in your way.
4. Now remove back portion of the waistband, ripping the seam until just in front of the seams that run down the outside of the legs). The waistband will still be attached in the front. There is no need to remove it.
5. Flatten out the loose waistband (so the seam that was at the top of it is now in the middle) and cut out the portion you marked. REMEMBER to adjust your cuts for seam allowances of a quarter-inch or so!
6. Fold one side of the cut band downwards and to your mark and place it over the other side on top of the other mark, so that your two marks are touching. Pin and sew. I used a straight stitch.
You may want to try this on now, to see if the waistband is the right size before you go any further!
7. Fold back together and pin the waistband back on, the way you found it, from the center to about an inch away from each side-seam. All the excess fabric will run to each side. Remember to align the new seam you created with the back belt loop (So that when re-attached, the belt loop will cover the ugly seam).
8. Now, as you will notice, the waistband no longer fits the top of the jeans! You will need to make up for this at the sides of the jeans. Notice that there is stitching on the outside of the side seams of the jeans that runs for roughly 5 inches. You need to remove these stitches as well as all those you find underneath (I found two more sets—jeans are meant to be strong) up to that 5-inch point (the point the outside stitching ends.)
9. Now push the extra fabric into the jeans and taper it off until you hit the 5-inch mark. We don’t want any strange bulges. Pin and straight stitch over the exact spot you removed the stitches from the front (You will probably be able to easily tell because the jeans will be either be darker underneath the original seam or there will be visible marks from the original stitching anyway.
You may want to add more stitching on the underside, considering how many stitches you actually had to remove. I didn’t, however, and I don’t think it’ll be a problem
10. You might want to try them on again before going any further and cutting off the excess fabric from the inside. After this, you have only to re-sew on the waistband (which SHOULD fit perfectly over the body of the jeans) and re-attach the belt loops. They will not be attached in their original positions. Just go straight up. Straight-stitch the waistband with your golden thread exactly where the original stitches were (you’ll be able to tell).
You can reattach the tags you removed, too, if you want to. I didn’t.
Here are the pictures of the finished jeans:

new center seam on inside. notice the two dark marks where the tag used to be attached. Notice how big the tag is!

new center seam hidden under belt loop

new side-seam

new belt-loop placement beside the ghost of the old belt loop placement