The 28-year-old explained she had lost three stone in three months and was one stone off her pre-pregnancy weight.
She added: “Honestly though... I’m really not in any rush to tackle that last stone, it’s not about what I weigh, it’s about how I feel and I feel pretty good.”
McGuiness said she’d “love to see” her abs again for the summer, but would only workout if she could fit it around her babies.
“I’m grateful my body has given me three miracles,” she added, alongside the hashtags: #4MonthsPostPartum, #MumOf3 and #TwinMum.
The mum to four-month-old Felicity and three-year-old twins Leo and Penelope was showered with compliments by fans.
“Wow you just look incredible Christine,” one fan wrote. “This is inspiring me to get my butt in gear and do some postpartum fitness.”
Another wrote: “Good lord you look great. Amazing mumma.”
McGuiness has been documenting her postpartum life on Instagram since giving birth in September.
In October 2016, she shared a photo of her post-baby body two weeks after Felicity’s birth.
“I have lost a lot of muscle tone, I have cellulite, loose skin and my body is nothing like it used to be,” she wrote on Instagram at the time.
The mum was praised by fans for “showing what a real body looks like” after birth. One woman wrote: “You keep doing what you do, amazing, inspiring and a decent woman all-round. More celebrity mums need to do this.”