Kayla Itsines

Itsines traces her interest in fitness to playing basketball and other sports. She recalls being initially intimidated and overwhelmed by the gym, until a personal trainer encouraged her to "just start somewhere". Finding that she enjoyed how the workouts made her feel, she abandoned her original plans to become a beauty therapist graduating from the Australian Institute of Fitness at the age of 18 as a Master Trainer. As of 2018 her wealth is observed as $63 million.

In March 2016, Time's named Kayla one of the 30 most influential people on the Internet, noting her success at leveraging social media to promote her brand. As of October 2016, Itsines had eight million followers on Facebook and five million on Instagram. Her Facebook followers had liked her content 7.7 million times.

In October 2016, Itsines and her partner, Tobi Pearce, were included in the BRW "Young Rich" list of the wealthiest Australians aged under 40 who had not inherited their money. Their fortune was reported at $46 million, in 2016. Itsines is one of only two among the 2017 AFR's Rich List that are of Greek heritage.

In November 2016, Pan Macmillan published Itsines' first print book, The Bikini Body 28-Day Eating and Lifestyle Guide. In August 2017, she announced the upcoming publication of her second book, The Bikini Body Motivation & Habits Guide, which will be available for purchase in November 2017.

In 2015, she embarked on a world tour, the "Kayla Itsines Bootcamp World Tour", leading free group fitness classes. The tour included Australia's capital cities, New York City, Los Angeles, and London.

In February 2015, Itsines took legal action against another Adelaide-based personal trainer, Leanne Ratcliffe, and Ratcliffe's partner Harley Johnstone over comments that they had posted on their YouTube channels. Ratcliffe, publishing under the pseudonym "Freelee the Banana Girl", had claimed that the BBG eating plan required users to starve themselves, and Johnstone, publishing as "Durianrider", claimed that Pearce used steroids. Itsines claimed the statements were defamatory. She obtained an injunction to prevent the further publication of the videos. When the complaint was heard in the Supreme Court of South Australia on 23 March, Judge Withers directed the case proceed to trial, but the matter was eventually settled out of court.

In April 2015, Apple featured Itsines in an advertisement for the Apple Watch, demonstrating the heart-rate monitor feature of the product.

She also started training her sister's friends who wanted to improve their fitness so they could play Netball on their high school team, focusing on building core strength and powerful legs. She lectured them on nutrition, and asked them to take before-and-after photos of themselves to track their progress. Itsines' 12-year-old cousin suggested using Instagram as a way of organising the photos. Within a few months, Itsines has gained hundreds of thousands of followers and was receiving regular requests for advice and help. Her partner, Tobi Pearce, suggested that she compile her routines into ebooks that could be sold online. In March 2013, they founded the Bikini Body Training company with Itsines as director and Pearce as CEO. The following January, they published the first two Bikini Body Guides, with Itsines' workouts in one volume, and nutrition information from dietitians Julie Dundon and Anne Schneyder of Nutrition Professionals Australia in another. Itsines would later offer the guides via an affiliate program as well. By October, the guides had been downloaded over one million times.

Itsines met her fiancé, Tobi Pearce, at a gym. They have lived together since 2012. In April 2018, they got engaged.

Itsines gave up drinking alcohol since at least 2012. She gave birth to a girl , Arna, in May 2019.

Kayla Itsines (/ɪ t ˈ s iː n ə s / it-SEE -nəs; born 21 May 1991) is an Australian personal trainer, author, and entrepreneur with Greek heritage. She is the creator of a series of fitness ebooks titled Bikini Body Guides, and a meal-planning and workout app, Sweat with Kayla. Sweat with Kayla generated more revenue than any other fitness app in 2016.