lower abs are smaller than upper abs

So I didn't know that the ab lift that I do at the gym focused on the upper abs. I have found out now, since I've been doing it for about 10 weeks, and my upper abs are firm (under my blubber) while I have little lower ab muscle. I've started doing the exercise where you sit in that "chair" thing and lift your knees up to your chest...3 sets of 15. Should I back off doing my upper abs for awhile and let my lower abs catch up or what?

Your upper abs come in much much easier than your lower abs do. Even when you do abs workouts that target the top and bottom, it seems your top always feels more worked out, and gets toned quicker, as well. This is just because fat covers the lower tummy, and not the upper tummy. Slow and consistent movements, like Pilates, help with the lower abs. I had this exact same problem, and Pilates actually is helping with my lower abs. Your upper abs will always get toned quicker, you just gotta stick with it!

there really isn't a upper and lower ab muscle, it is all one muscle. so if you do crunches it will work your entire abdominal wall, so will leg raises. it is impossible to flex just one part of muscle. miisris is right with the fat deposits, it loves the waist area. that fat is normally the last to go away, as long as you watch your eating and do your  cardio and weights your midsection will improve overtime.

I would work your lower abs, but not to much.  Until you lose enough weight, it's just going to push out your layer of fat.  Most people have a "six pack"- it's just under a layer of fat.  The only way to  lose it is through diet and exercise.  The benefit of working your abs is to improve posture, and help hold your stomach in. You use your abs to do lots of things.