Despite being married to a personal trainer, the 33-year-old “Me & U” singer had a “depressing and confusing” time trying to lose the 60 pounds she gained during pregnancy.

“I lost 20lbs within the first couple of weeks which I was told was normal and then another 10 gradually over the next 2-3 weeks,” she wrote in an essay for Almost Home last week. “I started to workout when I had a goal of 30lbs to go and when my doctor cleared me to. I went pretty hard at first. By mid March I was down another 15 and feeling pretty good. I had a bit of unexplained anxiety, but I was able to work through it…”

With only 15 pounds to go to be back at her pre-baby weight, Cassie said she suddenly gained 15 pounds back, which prompted her to go to the doctor.

“After a few weeks of bloodwork I found out that I had something called postpartum thyroiditis,” Cassie explained. “Basically my thyroid was hyper for a short period (hence the anxiety and weight loss) and then slowed down causing me to gain weight back.”

Having learned about her body, Cassie began to pay closer attention to her diet, which still yielded frustrating results.

“The next 3 months following were confusing and depressing to say the least. I changed my diet paying attention to things that I reacted negatively to (ie, bloating),” she continued, adding that she followed a special diet to avoid having her thyroid issue develop into Hashimoto’s Disease, which Gigi Hadid has discussed.

“I had completely lost my mind, but I’m glad that I did. I needed to understand what was happening with my body,” she wrote. “I went from creating and bringing life into this world to trying whatever I could to get back to feeling like myself again. It wasn’t about my weight anymore, it was about being happy, feeling good and not developing a disorder I’ve never heard of.”

The “Long Way 2 Go” songstress acknowledged that her husband, Alex Fine, being a personal trainer might make getting back into fitness easier, but admitted she had no desire to exercise.

“Truth be told, Alex spent those months in quarantine with me trying to drag me out of my slump to workout because he wanted me to be happy again,” she shared, “but more often than not I didn’t budge.

“I finally started working out 2-3 times a week and I’ve gradually moved up to 5-6.”

Cassie said that she wanted to share her difficult journey to highlight how differently each person’s postpartum body will react. Gaining 60 pounds, she said, “had many negative physical effects” and resulted in her going to sessions at a sports rehab facility to right her body’s wrongs.

“As women, (not all of us, but a decent amount) we put so much pressure on ourselves to look a certain way when I think what we should be focused on is our overall health and happiness,” she wrote. “…Whatever your goals are, choose to be healthy.”