Why you should swerve 'water fasting', according to an expert dietician

water fasting
Thinking about water fasting? Read this firstjosh hodge

Amid an Ozempic craze in Hollywood, TikTokers have come up with what they are claiming is ‘nature's version’ of the unofficial weight loss method – water fasting.

With over 112k posts under the hashtag #waterfasting on Instagram and the term ‘intermittent fasting’ trending on TikTok, with various videos suggesting that water fasting can reduce the risk of cancer and intermittent fasting is ‘the cure to the obesity crisis’ – it seems our obsession with intermittent fasting – which involves alternating between periods of eating and not eating – is becoming increasingly popular. But what about more extreme forms of fasting, such as water fasting?

If you’re considering water fasting, talk to your GP or ask a healthcare professional for guidance first.

What is water fasting?

Water fasting, which involves avoiding eating or drinking anything other than water for a set period of time, typically lasts for at least 24 hours – with people citing religion and weight loss as the number one reasons for trying it.

But although water fasting is trending on social media right now, it's not a new idea. In fact, humans have been fasting for thousands of years; the Greek physician Hippocrates recommended abstinence from food and drink for patients suffering from particular symptoms or illnesses in the 5th century BCE.

How do you water fast?

To date, there is no substantial medical research on water fasting, which means there are no specific guidelines on how to do it. Telling, huh?

A recently published study from earlier this year saw participants undertake a 7-day water-only fast, but this was in a controlled environment with medical support and replicating this at home isn't necessarily safe.

People on social media recommend water fasting for anywhere upwards of 24 hours, but, again, there’s no research to suggest any duration of time spent depriving your body of food and only consuming water will benefit your health.

Is water fasting safe?

According to registered dietician and director of City Dietitians Sophie Medlin water fasting for long periods of time isn’t a safe or effective approach: ‘There's no research around it because it's very dangerous,’ she tells Women's Health. ‘I'd highly discourage it.’

Is water fasting good for weight loss?

One of the reasons people might choose to water fast is to lose weight, but according to Medlin, it isn't a healthy way to lose fat. ‘You might lose some fat mass but on this diet, you'll mostly lose protein, muscle mass and fluids,’ she explains. ‘This means that any weight that you see lost on the scale you'll very quickly regain when you stop water fasting.’

Can you detox your body by water fasting?

Perhaps you’re considering water fasting as a way to ‘detox’ your body after a particularly indulgent weekend. Well, the truth is, depriving your body is no way to detox it after a few days or weeks of unhealthy eating. In fact, it’s probably going to make you feel worse. Plus, the human body is clever – it detoxes itself (your liver, kidney, bowel, and lungs all play a role in essential detoxification).

‘When we do things like water fasting or juice cleanses, we're actually asking our body to work harder because it's not getting normal nutrition or the nutrients it needs to allow our organs to work properly,’ Medlin says.

‘So, in fact, what happens is you end up with more toxins in your system produced by your body, and it makes the problem worse.’

If you’re looking for a way to nourish your body, a better idea is to focus on good nutrition. ‘Drink enough water and make sure you’re putting the nutrients in that your body needs every day and taking care of your body rather than punishing it,’ Medlin says. And if you need a healthy dietary patter, look no further than the Mediterranean diet.

What are the benefits of water fasting?

Without sounding like a broken record, there is no scientific research to suggest that water fasting is a safe way to improve your health or lose weight.

One study of 48 people who were overweight or obese found that water fasting for 17 days reduced their blood pressure. However, researchers concluded that there are many ‘questions about the long-term health effects and durability of outcome,’ and that more studies are required to assess the safety and effectiveness of water fasting.

Another study published in the journal Nutrition, Metabolism and Cardiovascular Diseases in 2013 looking at 30 adults who water fasted for 24 hours found that it could lower levels of triglycerides (which is a risk factor for heart disease) in the blood. But again, researchers concluded that the long-term consequences of these short-term changes are unknown, so it isn’t a foolproof method.

Are there any risks associated with water fasting?

The risks of water fasting far outweigh the benefits, which is why plenty of experts, including Medlin, say that it's not a safe diet to follow.

‘[Water fasting] is not considered safe and one of the reasons for that, especially when people do it for a long period, is that it can deplete their electrolytes, like sodium, potassium, and magnesium, which are essential for basic things like your heart beating and your lungs being able to breathe,’ Medlin says.

This means that water fasting, even for a short period of time, could potentially have a very negative impact on your health in the long term.

A 2021 study saw several negative health outcomes for its male participants who did an eight-day water fast. Although they lost weight and felt less stressed, they experienced a number of negative side effects, including dehydration, low sodium levels, low blood sugar levels, and an increase in uric acid in their blood (which can lead to gout and kidney stones).

On top of this, water fasting will deprive your body of vital vitamins and nutrients that it needs to function. ‘You're not getting any vitamins, minerals, carbohydrates, fats or proteins, which are completely essential,’ Medlin says.

The bottom line? Avoid. Water fasting is not rooted in science, so just keep scrolling.

Cut through the noise and get practical, expert advice, home workouts, easy nutrition and more direct to your inbox. Sign up to the WOMEN'S HEALTH NEWSLETTER

Breakfast ideas to try in the AM...

You Might Also Like