Apparently, this is Elle McPherson's "weight loss secret". So we called in a dietitian.

Well! In case you missed it, Elle McPherson’s trainer says the secret to the body of your dreams is some Epsom salts.

James Duigan, personal trainer, ‘wellness expert’ and trainer to the stars writes in his book the best way to lose body fat and slim down is not only by cutting out “bad” carbs and processed foods but by burning fat in the bath.

“If a client is getting ready for a photo shoot or a holiday, I tell them to soak in Epsom salt in the days leading up to it – the salts are full of magnesium and encourage the body to shed toxins quickly (and remember; these toxins encourage water retention and cling on to fat),” he writes in his best-selling book, Clean & Lean Diet: Flat Tummy Fast.

He calls it his ‘skinny bath’. Lie down in some water and, well, stay there. Huzzah. Body of your dreams.

It sounds too good to be true. Is it too good to be true? It must be too good to be true.

According to dietitian Zoe Nicholson of Love What You Eat, the idea that bathing in Epsom salts helps “shed toxins” and aides “slimming down” is “more or less nonsense”.

“Our body has a perfectly capable detoxing system with our liver and kidneys. The liver takes up toxic substances and converts them into harmless substances or makes sure they are released from the body. The kidneys extract waste from the blood for elimination from the body. If you’re drinking excess alcohol or eating a nutritionally poor diet, then addressing this is what you need to do to ensure the bodies own detox system is working efficiently,” she says.

Nicholson says she doesn’t encourage her clients to use Epsom salts in their diet or lifestyle routine for any purpose, though she acknowledges soaking in a bath with any kind of salt can help the muscles relax.

"The effect of Epsom salts on various aliments has plenty of anecdotal evidence, but there isn't much actual evidence to back this up. That said, the placebo effect is real and powerful and if an Epsom salt bath makes you feel better, then enjoy!"

She adds that if women are conscious of their weight and health, there are things outside food and exercise that have an impact on overall wellbeing.

"Mental or emotional health, stress and sleep are all factors that can significantly impact on a person's body weight and health. Each of these can effect the stress hormone cortisol along with appetite hormones and impact on weight.

"If you feel unhappy in your body, all of these factors can make you more vulnerable to this dissatisfaction and this can further impact on food choices, food cravings and emotional eating. Body image, or how we feel about our bodies, is a much under-acknowledged driver for eating behaviours that effect weight, exercise levels and health. What many women need to do is to start to address their body dissatisfaction if they truly want to improve their diet and health."

Unfortunately, Nicholson says, there is no "magic solution" to achieving a body like, well, The Body's body.

She says it comes down to "mostly genetics... no amount of detoxing or cutting out carbs is going to work."

So... that's a no to Epsom salts we think.

For more from Zoe Nicholson, you can find her website here and Facebook page here.

Listen: Brigid Delaney Tried The 101 Day Detox Diet So You Don't Have To: