Colon hydrotherapy is said to be great for toning the colon muscles, which helps in maintaining and resuming regular bowel movements. Photo / Getty

Sinead Corcoran dresses as Winnie the Pooh for her latest wellness experience.

On arriving at Auckland's Colon Care Centre, I was given a T-shirt to wear on my top half (nothing on the bottom half obviously, like Winnie the Pooh, no pun intended). At first, I wasn't sure why I needed the T-shirt, but more on that later.

Colon hydrotherapy, traditionally known as colonic irrigation, gently fills the colon with warm, sterile filtered water through a small, sterile rectal tube. When the water is flushed out, it carries with it any material that has built up in the large intestine, including waste matter, toxins and trapped gases. It's also said to be great for toning the colon muscles, which helps in maintaining and resuming regular bowel movements.

"Our clients tell us they experience a wide range of benefits after their colonics, including more energy, clearer skin, weight loss, better eyesight, better ability to conceive, less body odour or bad breath, less craving for bad food, better taste buds, improved posture, flatter tummies, stronger immune function, relief of headaches, less fatigue, better mood, improved bowel function and improved overall wellbeing," says the Colon Clinic's website.

To begin, I clambered up on to the "bed", which looks like a plastic dentist's chair with built-in stirrups. In the middle of the bed was a plastic hose the size of a small finger. I had to slide my body down the bed until I reached the hose, then kept sliding down until it was inserted.

Then, an extremely lovely woman came in and turned the tap on, at which point my life flashed before my eyes. She told me to stay calm and breathe, to relax my body and mind and told me it was a mental challenge more than a physical one.

For the next 40 minutes water gushed up inside me. Every 30 seconds or so, my stomach was so full it felt like it may burst. Then, with encouragement, I had to push all the water out. Then you literally rinse and repeat.

I was both freezing cold and sweating bullets at the same time. I didn't know if it had been a minute or an hour, because time lost all meaning. I also felt quite nauseous, which apparently is a normal side effect.

The health benefits of colonics have long been endorsed by celebrities, and most famously, my all-time hero, Princess Diana.

Allegedly, as well as removing harmful toxins from the body, colonics are supposed to encourage the growth of healthy bacteria, boost the immune system and even help weight loss.

However, the treatment isn't without risks. Multiple studies note side effects include cramping, bloating, nausea, vomiting, electrolyte imbalance and renal failure.

I tried really hard to stay calm and stick it out, but I had to end the treatment 10 minutes early. I'd love to tell you I felt amazing afterwards and went from a size 16 to a size 10 immediately, but I didn't really notice a difference, however you do apparently need a few sessions to see results.

Would I recommend it? Well despite my experience, I am considering giving it another go before my wedding in a deeply sad attempt to get a flat stomach for my photos. And apparently the first time is awful for everyone because it's such a shock to the system – my friend who has them done religiously says the second time you go it's absolutely fine.

However, this treatment may not be for everyone.

And the T-shirt? When you get yourself off the bed after colon hydrotherapy, it's possible your back may be covered in a bit of a mess, much like a baby after a nappy accident.

Charles III's coronation is reportedly set to last just over an hour.