Kayla Itsines is an Australian personal trainer, author, and entrepreneur from Adelaide, South Australia. She was born on 21 May 1991 and grew up in a Greek-Australian family. She is co-founder and head trainer of the women’s fitness app Sweat, and one of the most recognizable fitness figures on Instagram at @kayla_itsines.
She did not start as an influencer. After high school she trained at the Australian Institute of Fitness and qualified as a master trainer at 18. She has said she first found the gym intimidating, then stuck with it because the work made her feel better. Instead of becoming a beauty therapist, she began training women one-on-one, including sessions in her parents’ backyard with a whiteboard. Those early clients were the template for everything that followed.
Instagram turned the local trainer into a global brand. Women started asking for the workouts she used with clients. In 2013 she and then-partner Tobi Pearce founded the Bikini Body Training Company. In January 2014 they released the first Bikini Body Guides, PDF programs built around short, high-intensity sessions — originally three 28-minute workouts a week. The guides spread through before-and-after photos and a growing female following. The app Sweat with Kayla launched in 2015 and was later rebranded Sweat, a broader platform with multiple trainers, recipes, and programs. In 2016, Time named her one of the 30 most influential people on the internet. That year Sweat was also reported as the highest-grossing fitness app.
The business got big enough to sell. Sweat went to iFIT in a deal widely reported around US$400 million. Itsines later bought the company back and returned as owner, saying she wanted control of the product again. The programming shifted with her own training. The old BBG look-focused branding gave way to Sweat as a women’s training app. She still offers the original high-intensity work, now often called OG Kayla, but has moved her own routine toward strength, plus pregnancy and postnatal programs. She is certified in pregnancy and postnatal exercise and has been open about endometriosis surgery, postpartum training, and training differently in her 30s than she did at 20.
Her personal life has been public because the brand was built on it. She and Pearce became engaged in 2018 and had a daughter, Arna, in 2019. They announced their split in 2020 and have co-parented since. Itsines later began dating Jae Woodroffe, announced their engagement in 2022, and married him in December 2023. They have a son, Jax, born in January 2023. She has also talked about other businesses, including a dog-training app and commercial property.
What made her last was not one viral workout. It was a simple offer that scaled: short sessions women could do at home, a community posting progress, and a trainer who kept showing up after the first boom. Sweat is no longer just “the BBG girl.” It is the company she started in Adelaide, sold, bought back, and still fronts.