Kourtney Kardashian Reveals Her Go-To Drink for a Flat Tummy

When it comes to diet and fitness tips, Kourtney Kardashian has it covered. Not only has she majorly stepped up her fitness game over the past few years, but she's also widely known as the "health nut" of the Kardashian sisters.

💙 on my app

A post shared by Kourtney Kardashian (@kourtneykardash) on

So when she announced on her app that she drinks the same thing every day to keep her energy levels up and help flatten her tummy, you can bet that we were all ears. And no, it's not coffee that keeps her perky throughout the day; it's green tea.

Apparently, coffee hasn't even been a part of the 38-year-old star's daily routine for more than 15 years.

“First off, I’m allergic to coffee—it makes me insane! I get really hyper and really on edge when I drink it, so I stopped drinking it when I was 21 or 22,” Kardashian wrote, calling green tea her "go-to."

Up Next: Kourtney Kardashian's See-Through Swimsuit Takes Cheeky Swimwear to a New Level

While green tea has less caffeine than coffee (sometimes even up to half the caffeine as coffee, depending on the brew), the eldest Kardashian sister says it's able to deliver caffeine “much slower than with espresso or coffee, so it lasts longer.” Plus, she says it helps with her mood as well as her fitness.

“I swear it makes my tummy flatter! Also, green tea can help reduce the signs of cellulite,” she wrote. She even encourages her followers to drink an "extra iced green tea" for an energy rush before a workout.

all week🍦🍔

A post shared by Kourtney Kardashian (@kourtneykardash) on

She says that she'll usually drink a hot green tea in the "late morning or early noon," and she takes it with "a cup with honey and a little splash of almond milk" when she's at a restaurant.

More: Get a Butt Like Kourtney Kardashian With Her 2-Step Booty-Boosting Workout

When it comes to other healthy eating rules Kardashian lives by, she says that she cut gluten and dairy out of her and her children's diets completely.

"I have noticed a great positive change in behavior with my children when we stick to a gluten-free and dairy-free diet," she told PEOPLE. "I don’t think everyone needs to eat this way but we had muscle testing done, which showed we all have sensitivities to corn, gluten and dairy."

She also avoids sugar, which in turn means soda, juice, cocktails, store-bought salad dressings, etc. Plus, she drinks apple cider vinegar, which has been known to help aid digestion and boost metabolism, on the daily. "I drink a ton of water during the day and I also drink a glass of water mixed with 2 tablespoons of apple cider vinegar twice a day (in the morning and at night),” she wrote on her website.