Kourtney Kardashian is "allergic" to coffee.

Kourtney Kardashian

Kourtney Kardashian

The 38-year-old reality star - who has Mason, seven, Penelope, five, and Reign, two, with her ex-boyfriend Scott Disick - has admitted she was forced to give up the caffeinated beverage in her early 20s after she realised drinking it made her "insane".

Writing on her blog, Kourtney said: "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."

Instead, the 'Keeping Up with the Kardashians' star sips on green tea as her "go-to" hot beverage, and even believes it helps keep her stomach looking flat.

She added: "[Green tea is] my go-to. I swear it makes my tummy flatter! Also, green tea can help reduce the signs of cellulite. [I have a] hot green tea late in the late morning or early noon. [My favourite is] a cup with honey and a little splash of almond milk - that's my thing at a restaurant."

That's not the only health tip the brunette beauty - who is currently in a relationship with former boxer Younes Bendjima - has shared recently either, as earlier this month she opened up to her followers about her detoxing routine.

She said: "First of all, detoxing, of any kind, should be something you consult with your doctor about beforehand, since everyone is different.

"My doctor did muscle testing and found that I had high levels of metals like mercury and lead, so my motivation for this detox is to get rid of the metals in my system.

"I don't eat for 14 to 16 hours after dinner (known as intermittent fasting), so if I have dinner at 6 pm, I won't have breakfast until 8 am or 9 am.

"I also do a 24-hour fast one day a week.

"On the fasting days, I drink bone broth and water all day, and then I'll have dinner that evening.

"I find it easiest to always do this on a very busy day, so I don't have time sit around and wish I was eating."