This is bodyfat impedance, which is notoriously finicky. Your hydration levels, electrolyte levels, relative humidity, etc can affect these results significantly. I believe Christian Thibaudeau mentioned seeing a 10% fluctuation (or somewhere thereabouts) in BF% from morning to evening based on BF Impedance readings.
Effectively, it’s an expensive machine that gives you bad metrics. Sorry, your dietician should know better than this. A Dexa scan is pretty accurate, but still has some variance.
I don’t know how else to say this… You are not gaining 2lbs of muscle in 3 weeks. You could be losing that much fat in 3 weeks no problem, but not whilst also surpassing the muscle accumulation rate of the rest of the planet.
What I’m saying is, the only method you have to measure muscle gain/fat loss is a tool that is highly subjective - and this is why you are seeing random LBM gains and losses.
Your weight is staying the same because you are eating at maintenance. Your bodyfat and muscle mass are likely unchanged because you are eating at maintenance, but your dietician’s flawed measuring system is telling you that your body breaks the rules that everyone else’s body follows. There is nothing new or unusual about your ancestry, it isn’t just ‘some weird thing your body does’, it’s a bad tool that’s erroneously trusted by misinformed professionals.
Feel free to google the accuracy of bodyfat impedance testing. I think this will answer why you’re seeing literally unprecedented body composition changes with no change on the scale.
Respectfully, this is not the physique of someone who possesses superhuman body composition abilities.
I hope this isn’t coming off as mean; often my comments do. I’m genuinely hoping that this helps you, and I hope you know that I’m on your side - even if it sounds like I’m being a dick (i kind of am a dick, so no worries).