She’s known as one of the most outspoken celebrities on the planet: there’s no thought, no moment and no emotion that 31-year-old Chrissy Teigen keeps from her fans.

But in a raw and emotional essay for the April issue of Glamour magazine, the former Sports Illustrated model has revealed to fans that she has been battling postpartum depression since the birth of her daughter Luna in April last year.

“To a lot of you, I think, I seem like the happiest person on the planet,” she wrote, before admitting that for most of last year, she felt incredibly unhappy.

I’ll just say it: I have post partum depression. So much love to @glamourmag for letting me share something that was eating me up inside for months and months. One of the most amazing things about social media is the ability to interact candidly with friends and fans and it felt so weird knowing what I was going through but not really feeling like it was the right place to speak on it. I’ve always felt genuinely close to all of you and I’m insanely relieved you now know something that has been such a huge part of me for so long. My full essay is on the @glamourmag bio. ❤

A post shared by chrissy teigen (@chrissyteigen) on Mar 6, 2017 at 9:24am PST

“I had everything I needed to be happy…How can I feel this way when everything is so great?” she said.

“I’ve had a hard time coming to terms with that, and I hesitated to even talk about this, as everything becomes such a ‘thing’. But it’s such a major part of my life and so, so many other women’s lives.”

Chrissy shared that despite her work – as a host of the Emmy-nominated Lip Sync Battle – going above and beyond to make her transition back into her job as smooth as possible, she found it difficult to get out of bed each day.

“My lower back throbbed; my ­shoulders—even my wrists—hurt. I didn’t have an appetite. I would go two days without a bite of food, and you know how big of a deal food is for me. One thing that really got me was just how short I was with people,” she said.

Headed to Beauty and the Beast! @laurapolko @allanface @monicarosestyle ❤

A post shared by chrissy teigen (@chrissyteigen) on Mar 2, 2017 at 6:36pm PST

When she didn’t have to work, Chrissy said she never left the house.

“Most days were spent on the exact same spot on the couch and rarely would I muster up the energy to make it upstairs for bed. John would sleep on the couch with me, sometimes four nights in a row,” she wrote.

6 months old!

A post shared by John Legend (@johnlegend) on Oct 14, 2016 at 3:03pm PDT

“I started keeping robes and comfy clothes in the pantry so I wouldn’t have to go upstairs when John went to work. There was a lot of spontaneous crying.”

The model said her whole demeanour had changed: “Before, when I entered a room I had a presence: head high, shoulders back, big smile…Suddenly…I would keep my hands on my belly and try to make myself as small as possible.”

Listen to the latest episode of Mamamia’s parenting podcast, This Glorious Mess:

It wasn’t until a GP diagnosed her with postpartum depression and anxiety that she began to make sense of what she had been feeling.

“I remember being so exhausted but happy to know that we could finally get on the path of getting better,” she wrote.

“I started taking an antidepressant, which helped. And I started sharing the news with friends and family—I felt like everyone deserved an explanation, and I didn’t know how else to say it other than the only way I know: just saying it.”

Last night!! Had so much fun celebrating @directvnow with @si_swimsuit here in Houston! And love to my babies @daniellepriano @allanface and @monicarosestyle!!!

A post shared by chrissy teigen (@chrissyteigen) on Feb 5, 2017 at 2:04pm PST

Chrissy is also well-aware of the fact that she never thought postpartum depression would affect her.

“I have a great life. I have all the help I could need…But postpartum does not discriminate. I couldn’t control it,” she said.

“And that’s part of the reason it took me so long to speak up: I felt selfish, icky, and weird saying aloud that I’m struggling. Sometimes I still do.”

The model and personality wants to use her experience to help others speak up when they are feeling alone.

“I’ve hated hiding this from you,” she ended her emotional note.