"Another photo from my postpartum throwback that I haven’t shared until now," she wrote alongside a sweet shot of her breast feeding an infant Arnie.
"There are a lot of things they don’t tell you about what happens after birth. I didn’t know I’d look pregnant for so long after I had a baby. I hadn’t seen many postpartum bodies, if any. No one told me. But it’s normal.
"I’m smiling because I’m so proud of Arnie. My body delivered a healthy boy and I’m beyond euphoric to have him safe in my arms. I’ll work out how to do up my pants (and my jacket) later 😂," she finished, adding the hashtag #bounceforward which she uses to encourage women to become better versions of themselves after giving birth.
The 34-year-old fitness queen, who is the founder of online exercise programme TIFFXO, regularly posts uplifting messages to women, particularly mothers, encouraging them to be realistic with their health and weight goals.
Tiff previously revealed she gained 30kg whilst pregnant and took a solid 17 months to "regain fitness and strength".
Her advice to first-time mums is to take it day by day, focusing on the fit and not the fat loss.
The businesswoman swears by consistent training, a moderate diet and engaging in exercise you enjoy as her key to maintaining her incredible physique.