How does Kourtney Kardashian stay so slim? The secret is her detox diet — and it's insanely strict.

The oldest Kardashian sister shared the secret behind her enviable figure on her app this week, and let's just say you'll be hungry after reading this post.

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Along with enjoying just three meals a day, Kourtney also detoxes for one day each week, according to People.

So how exactly does the mother-of-three detox? By drinking just water and bone broth, of course.

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Her three meals are low-carb and high in protein and fatty acid. For breakfast, she enjoys minimal fruit (because you know, sugar), and sticks with her favorite avocado smoothie. Lunch and dinner are typically fish or chicken with cauliflower rice or broccoli. And she makes sure her fans know you can't have breakfast again until 14 to 16 hours after dinner.

In a nutshell, say goodbye to gluten, dairy, sugar,  and definitely no snacking — except for the occasional almonds!

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Kourtney is human (barely) and does admit the 24-hour detox is the hardest. "On fasting days, I try to stay busy and, if I’m home, I’ll avoid going into the kitchen,” the 37-year-old wrote. “I’m not going to sugarcoat it, this detox is difficult.”

That's putting it lightly.

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Double gym selfie.

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We'll just stick with Khloé Kardashian's diet, who eats seven meals a day, and isn't afraid to indulge in a cheat meal.

Her go-to meals include a protein shake for breakfast, chicken and veggies for lunch, and a "fatty" fish such as salmon or black cod for dinner.

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"She has a pattern where she will do seven days on and then have one meal off,” her nutritionist Dr. Philip Goglia told Healthista. “Her choice of cheat would vary a great deal – maybe she’ll have a slice of cake as dessert or a pizza or pasta dinner, basically whatever she has a craving for.”

We always knew we like KoKo better! For more sexy snaps of Kourtney, check out the gallery below!