Even at 15+% bodyfat, I've been able to get my upper abs to show clearly by doing weighted exercises: Cable crunches and weighted russian twists[1]. Looking back on it, I'd even say it wasn't that hard.
But still no lower abs. Those are harder for everyone, they say, and take lower bodyfat % than the upper abs. Since I've gotten such good results with weighted exercises to make the upper abs stand out, I'm looking for some similar options that target the lower abs. With weight.
How about it?
Footnote 1: For cable crunches, I'm up to 4 sets of 20 reps, working up from 70lbs to 90lbs as the sets go. For russian twists I'm currently doing 60 reps holding a 15lb weight. Since doing this for a few weeks, I'm really noticing results in my upper abs and obliques. It's easy/quick enough that I have no problem adding those exercises on 3-6 times a week. The 15% bodyfat number is where dexascan currently shows me.