Cassie and her personal trainer husband, Alex Fine, welcomed daughter Frankie Stone in December

| Credit: Cassie/instagram

Cassie is opening up about her fitness journey.

The 33-year-old singer — who welcomed daughter Frankie Stone, 8 months, with husband Alex Fine in December — got candid about her postpartum weight loss in a recent blog post titled "What Healthy Looks Like to Me," revealing that she "gained a total of 60lbs." while pregnant with her child and the weight "had many negative physical effects" on her body.

Cassie began by sharing a before-and-after photo of her 30-pound weight loss, writing that it was a "struggle" to document the transformation because she "didn’t even recognize" herself at first.

"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 shared. "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 and down another 15 meant I only had 15lbs to go to get back to my pre-baby weight."

However, Cassie said the weight loss "only lasted a couple of weeks" and she gained 15 pounds back, prompting her to undergo bloodwork that eventually led to a postpartum thyroiditis diagnosis.

"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," she explained. "From what my doctor told me it’s not super common. About 5-10% of women experience it within the first year after childbirth."

"The next 3 months following were confusing and depressing to say the least," she continued. "I changed my diet paying attention to things that I reacted negatively to (ie, bloating). I actually started roughly following an autoimmune diet (AIP) in fear that my thyroiditis would turn into Hashimoto’s Disease (an autoimmune disorder)."

Cassie admitted that she was overwhelmed with emotions following the diagnosis, writing, "I had completely lost my mind, but I’m glad that I did. I needed to understand what was happening with my body."

"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."

During that time, Cassie said she "went up and down with working out."

"It was discouraging. Once I started to become more consistent, I started to see and feel the results very slowly but it was happening," she shared. "I know a lot of people think, well she’s married to a personal trainer, it shouldn’t be hard for her or she should be in shape she has no excuse, but I was unhappy with myself. S— happens, I’m human."

The star went on to credit her fitness trainer husband for helping her stay focused "because he wanted me to be happy again."

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"I wanted to share my story because I want it to be a reminder that no two weight loss/get fit stories are the same. Gaining that much weight in pregnancy had many negative physical effects on my body," she wrote, explaining that she suffered back and neck pains as a result.

"Once I was able to rebuild my core strength a lot of my pain went away. Consistency was key. The program that Alex designed for me was the best gift he could have given me besides Frankie, of course," she added.

Looking back, Cassie said it "wasn’t easy in the beginning, but it was worth it and I’m so glad I didn’t give up."

"Today I’m in better shape than I was before the baby. I honestly don’t think I’ve ever been in this good of shape," the mom wrote. "Working out has given me a place to get rid of any negative energy and emotions that I might have, boost my serotonin and practice discipline. Every day that I workout isn’t perfect, but I show up and I push myself."

"Whatever your goals are, choose to be healthy. For me, this is what it looks like when I’m taking care of myself. This is what healthy looks like for me."