Kim Kardashian and her sisters' diet secrets revealed

Kim has dropped a substantial amount of weight since the birth of her second child, Saint. Photos / Getty

It seems like the whole Kardashian family is slimming down - most off all Kim Kardashian.

Now Khloe Kardashian has revealed what her famous sisters really eat to stay in shape.

Writing on her blog in a post titled "KHLO-FIT: My Sisters' Diets Are Cray", Khloe said: "You won't believe what my sisters actually eat".

"We all have such different eating habits that sometimes when we're trying to choose a restaurant I wonder if we're even related," Khloe, 32, wrote.

She said Kim's diet mainly consisted of "red meat and dairy", and she has cut out sugar and carbs to lose more than 30kg since the birth of her son, Saint West, in December.

Commenting on Kim's strict, meat-heavy intake, Khloe said, "I'm saying hell no to this" (as Khloe admitted she still eats sugar and carbs).

Kourtney, 36, has a strict organic diet and "only eats organic food and has pretty much convinced herself that she is allergic to dairy and gluten too," Khloe blogged on khloewithak.com.

Kourtney Kardashian always eats organic, according to her sister Khloe. Photo / Getty

Despite their enviable figures, Khloe's younger sisters Kendall Jenner, 20, and Kylie Jenner, 19, are into junk food, according to Khloe.

"She loves burgers and pizza and goes to In-N-Out all the time. Kendall is my go-to girl on cheat day," Khloe said of Kendall's eating habits.

Kendall and Kylie are big on junk food, according to their older sister. Photo / Getty

"Kylie eats like a typical teenager but she's also super aware of what she puts in her body when it comes to fresh and organic foods," Khloe said of her youngest sister, Kylie.

"It's all about that moderation."