Anthony, thanks for your suggestions. I adopted a form of intermittent fasting about 4 weeks ago after reading the leangains.com site. I eat only in an 8-hour window, and only 2 large meals per day, with a high-calcium snack like yogurt or cheese every 3rd day. I'm not perfect with this protocol, but I stick to it 5-6 days each week. I eat closer to 1900 calories on non-workout days, and closer to 2500 on workout days. When I deviate, I'm still low-carb/primal, but I "graze," eating for more than 8 hours and with smaller meals and snacks.
Also, I'm lifting as heavy as I can 3x/week. Here's an example from my most recent workout, adapted from "I Want to… Do a Pull-Up!
10 min. recumbent bike (low-speed)
Lat-pec stretch on foam roller
DB split squat (25x10x3)
DB incline press (30x10x3)
Plank push-ups (10x3)
Close-grip front lat pulldown (70x12, 85x10, 100x6)
Pushups (15 shoulder-width, 15 elevated, 15 spiderman)
Plank sets (3 sets, L. side w/flexing 30 sec., front 30 sec. . R. side w/flexing 30 sec.)
Band-assisted pullups* (10, 8, .5, 6); I estimate I'm lifting 50% of my weight
Standing wide-grip cable row
(23x12, 27x10, 30x8, 33x6)
DB bicep curl w/ shoulder press (12.5x12, 15x10, 17.5x8, 20x6)
HIIT cardio, 20 min.
Does this qualify as lifting heavy things?
I've built up to my current weight amounts and pull-up lifts over the course of 6 weeks, and I've hit my plateau. I have some limits on how much weight I can safely lift in the DB squat, due to knee problems (crepitus, aka crunchy knee syndrome) and shoulder/deltoid exercises (tight rotator cuffs).
Still, I'm stuck. I can do 1-2 unassisted pull-ups or chin-ups, and I can't make any progress in my bench press or military press. Am I just being impatient, or is it possible I've already reached my genetic potential?
*I stand on a huge rubber band slung over 2 parallel posts, then do a pull up where my hands grab 2 small handholds above me.