as someone with neither knowledge nor experience with the matter, the following does not even consist of smoke and mirrors. i am thinking of the relationship between bodyweight and medium-term strength potential as something like this: ok, we really need an 18-dimensional graph or something and the proportions here are all wrong. but my thought is that what you guys are describing sounds like you feel like you are in the "too much" zone, but at a local maximum of strength. that is, adding more weight will make things more difficult, but losing weight has other short-term effects that make you weaker (the little valley). however, perhaps with sufficient "toughing it out" and giving the body time to readjust will allow for greater gains in the new situation. i think we've all made the argument at some point that ditching 15lbs of fat should get us at least another 8lbs on squats or deadlifts. and certainly, with running/biking/whatever, you go faster when you can convince your kid that they don't really need that piggyback ride. also: suddenly, the knee-based dangers seem less perilous. anyways, be strong and of good courage!