I used to do weights (or so I thought), but I bought into the light weight
high rep propaganda that did nothing but overtax my joints.  With light, med.
weights, I too can get along just fine in ketosis.  But try really lifting ie
bench press weight that in which you can not do more that 8-10 reps or deep
squats and I'll bet you'll feel a real difference in your energy levels while
in ketosis.  My goal now is to stimulate growth hormone release (and improve
my body composition, not just "lose weight" or get smaller) in the most
effective, efficient way possible, and I'm hoping that high intensity short
duration exercise may give me better results.