Forty mountain climbers, 20 leg lifts, 20 toe touches, a 30-second plank, then repeat. That's just half of Day One's workout requirement in fitness celebrity Kayla Itsines' 12 week course. 

Itsines, a 25-year-old personal trainer from Adelaide, Australia, has taken Instagram by storm. She shares selfies of herself in workout gear and dramatic before and after photos of clients to show that her exercise program works.

Her social media presence has fueled a booming business. Itsines offers a 12 week program dubbed “bikini body guide” (or #bbg) and takes clients through a daily 28 minute workout with a corresponding meal plan for $52.95. She also offers an app, Sweat, that takes users through a similar workout through a mobile version of #bbg that costs users $19.99 per month and offers snack suggestions such as hard-boiled eggs and cucumbers. 

Itsines has the self-proclaimed ‘largest female fitness community’ with 15 million followers, but she isn’t the only one in the Instagram body guide game. Anna Victoria, creator of the Fit Body Guides, boasts 1.3 million followers on Instagram and offers a 12-week diet and exercise program run for $79.95.

Itsines and Victoria each attempt to foster communities of body positivity. Itsines told the Cut that “a ‘bikini body’ is when you feel comfortable in a bikini.” And Victoria has shared two side-by-side photos of herself to show how angles and lighting can make the same body look differently.

Still, the "after" photos of clients following the program tend to feature women with defined abs, muscled thighs, and taut arms. 

The programs stress that they are designed for women of all sizes and fitness abilities. But can a client really expect to see such a dramatic change in their body after a 12-week program?

“There’s so many variables that could dictate differences in the types of changes that people see in their bodies,” Jessica Matthews, a senior advisor on health and education for the American Council on Exercise, told ATTN:. “It would be completely inappropriate and unprofessional for me to say, ‘yes every single person who does this will see these results.’ Because that’s not the case. Every body responds to exercise differently.”

Matthews notes that these regimes hit many of the staples of an effective workout plan. They also meet the American College of Sports Medicine’s guidelines for time spent working out weekly, incorporating resistance training, cardio-respiratory training and focus on all the major muscle groups. 

But there’s still some room for improvement. Matthews said she wishes the programs included warm-ups and offered more variations to accommodate a wider audience, like modifications to increase or decrease the difficulty of individual movements.

Karina Knight, a registered dietician and founder of the California Nutrition Group, told ATTN: that the food guides are plagued by the same problem.

“Many of these generalized plans only include age, gender and physical activity, which is a good start,” Knight said, but that “ideally, [food guides] should be tailored for individual needs such as age, gender, physical activity, medical history, medications, and education.”

Itsines meal plans are between 1,600 to 1,800 calories a day and feature lots of smoothies, low-fat cheese, and small portions of avocado.

“From my experience, unless required for medical reasons, strict diets do not work,” Knight said. “People usually quit after 4-5 weeks and the main reasons are due to food cravings, unable to follow a strict diet in social situations, lack of time to prepare their own meals and most importantly, lack of family or social support.”

However, it's quite possible that the Instagram community can create a version of that social support network.

“What I think these programs have done so well is they’ve created communities around it,” Matthews said.

“Social support is a huge factor when it comes to the actual adoption and ultimately the adherence to a regular routine of physical activity.”