Before you blame the fat, look at the evidence on your own body.
Everything else responded. Your face got smaller. Your neck, your collarbones, your wrists, your hands — those all changed, and they changed fast. If what's left in your middle were simply fat, it would have come off in the same proportion as everywhere else. It didn't.
And it changes through the day. Flatter when you wake up. Softer and fuller by evening. Different after a salty dinner, a travel day, a bad night's sleep, a stressful week.
That's the tell. Fat doesn't behave like that. Fat comes off proportionally, and it does not fluctuate between breakfast and bedtime.
Fluid does.