>>76490404 (OP)
Depends on how strictly you want to interpret it. Having absolutely not weight changes is impossible, both because of normal variation (losing weight overnight through sweating, for example) and because fat and muscle have different densities.
It's possible to gain muscle at a similar rate to fat loss, though. You need to train (shocker), get sufficient nutrients, and most importantly, keep your hormones in a anabolic state, while simultaneously doing a caloric deficit.
In practice, unless you have good genes and are currently in the middle of puberty, the only way to do it is with massive medical support. In other words, roids, regular bloodwork, and medication. Never tried it myself, and from what I heard from people doing this stuff with animals for research purposes, it's not exactly safe.
