In the last few days I've seen a girl in her 20s be told that wanting a flat belly is unrealistic and a guy be told that sub 10% bf was largely genetics.
When I started my journey, I was obese and from Day 1 I had a "unrealistic" goal physique. It took me over a decade but I achieved that goal and so have hundreds of thousands of other people so why call it unrealistic? It's only so if you believe it.
Instead of discouraging someone looking to achieve something remarkable, why not just say "go for it!"?