"Even when it felt impossible, I chose to work harder," Jessica Simpson captioned a Tuesday photo post showing off her impressive weight loss

By Jen Juneau
September 24, 2019 03:30 PM
Advertisement

Jessica Simpson is celebrating a major fitness accomplishment.

The actress and singer, 39, revealed on Instagram Tuesday that she has lost 100 lbs. since welcoming her third child, daughter Birdie Mae, on March 19.

“6 months. 100 pounds down (Yes, I tipped the scales at 240 😜),” Simpson captioned a two-photo slideshow featuring both herself solo and one snap with her 6-month-old baby girl.

In the images, the star is wearing black sunglasses and a black midi dress, featuring long bell sleeves, a pleated skirt and a belted, cinched waist.

“My first trip away from #BIRDIEMAE and emotional for many reasons, but so proud to feel like myself again,” Simpson continued. “Even when it felt impossible, I chose to work harder. 💚”

Want all the latest pregnancy and birth announcements, plus celebrity mom blogs? Click here to get those and more in the PEOPLE Parents newsletter.

Credit: Jessica Simpson/Instagram

A friend of Simpson tells PEOPLE that she is “doing great” after celebrating husband Eric Johnson‘s 40th birthday this past Sunday “with close friends and family.”

“She’s working hard and working out and eating healthy and trying to get back in her best shape and excited for what’s ahead,” the source says of Simpson, whose upcoming memoir is set to be released on Feb. 4.

“She’s trying to get back to her healthiest place,” the insider continues. “And she just wanted to get to a place where she feels her healthiest. She’s not focused on the number, but on feeling her best self.”

While Simpson has not revealed how much she gained during her third pregnancy, according to the American Pregnancy Association, recommended weight gain during pregnancy varies based on pre-pregnancy weight. For women with a BMI of 18.5 to 24.9 (“average weight”), their guideline is 25 to 35 lbs.

RELATED VIDEO: Jessica Simpson Is Writing Her Memoir: “Love, Laughter, Tears and Truth” on Every Page

Simpson — who’s also mom to son Ace Knute, 6, and daughter Maxwell “Maxi” Drew, 7 — told PEOPLE in July that she was slowly but surely recovering post-baby, sharing that she was “working really hard” at the moment.

“It’s not easy at all, but I am determined to feel good. I have been doing a lot of walking — getting my steps in not only burns calories but it also helps me clear my head and get focused,” she said.

Along with her daily steps (Simpson previously told PEOPLE that she tries to walk three miles a day with her husband and their kids), she was also making improvements to her diet.

“I am eating healthy too — I discovered I really like cauliflower,” she revealed. “Who knew it could be a substitute for almost anything?!”