Gigi Hadid Gives Up the Tea On Her Killer Abs, She's No Kardashian

Gigi Hadid is a NO shortcuts kinda chick ... at least when it comes to her famously flat stomach.

Gigi was out in NYC with her bro, Anwar, and mom, Yolanda, when she tackled the question everyone's been asking this week after she was spotted showing off her abs.

The pic was reminiscent of scores of IG models, and Kardashians, who promote Flat Tummy Tea products -- but Gigi drove one point home with our guy: Do NOT lump me in with the K sisters!

Besides, her real secret is 21.