Does Fasting Work? Benefits of Juice Cleanses & Intermittent Fasting

If you’ve ever scrolled through TikTok or Instagram and seen someone raving about their “3-day water fast” - maybe even us guys at PRESS raving about our cleanses, then you might have asked yourself: does fasting even work? Is it just another health trend, or is there actually some science behind it?

Let’s break it down. Whether you're curious about trying a juice cleanse, wondering if fasting helps reset your gut, or figuring out if you can still hit the gym while doing it, we’ve got the answers. 

What Even Is Fasting?

At its core, fasting just means going without food (or certain types of food) for a set amount of time. 

Different Types of Fasting:

• Intermittent fasting (like the 16:8 method, where you fast for 16 hours and eat within an 8-hour window)
• Water fasting (where you only drink water for a set time) - only advised under proper supervision!
• Juice cleansing (where you only drink fruit/vegetable juices for a day or more)

It might sound intense, but humans have fasted for centuries - whether for religious reasons, cultural traditions, or health and it really does have some great health benefits.

Do Fasting and Juice Cleanses Really Work?

The answer depends on what you mean by “work.”

If you're expecting fasting to be a magic weight loss solution or instantly give you abs, you might be disappointed. But if you’re looking to reset your gut, improve your relationship with food, support toxin detoxification, improve insulin sensitivity or give your digestive system a break, fasting and cleansing can certainly help, especially when done safely and mindfully.

Some of the greatest benefits of fasting are its ability to reduce inflammation (chronic inflammation is a huge trigger for many diseases) and autophagy - a natural process in which cells recycle damaged or dead components which improves cellular function and ultimately health. Read more about the do’s and don’ts of a cleanse.

Is a Juice Cleanse Good for Gut Health? 

Your gut is home to trillions of bacteria (called your gut microbiome) that affect everything from digestion to mood. Eating junk food, stress, and lack of sleep can throw this balance out of whack. That’s where a monthly juice cleanse can come in handy.

Here’s what happens when you do a 1- to 3-day juice cleanse:

• You give your digestive system a break from heavy, processed foods.
• You flood your body with vitamins, antioxidants, and hydration.
• Replenish Nutrients: Fresh juices are packed with vitamins, minerals, and antioxidants that can help replenish your body's stores.
• Supports Detoxification: Juices made from leafy greens, citrus fruits, and other nutrient-dense ingredients can support your body's natural detoxification processes.

Think of it as pressing the "reset" button on your gut, not a long-term fix, but a helpful way to kickstart healthier habits. You may notice that your bowel movements change and you have fewer or even pass no stools during a juice cleanse. That's nothing to worry about as you're not eating any fibre rich fruits and vegetables which would normally bulk your stool. You should find your bowel movements regulate and (even improve) after a cleanse.

Nutritionist Tip: Look for juices that include things like celery, spinach, ginger, lemon, or turmeric (luckily here at PRESS we have these in abundance). It's best not to use smoothies with lots of purees in as part of a juice cleanse as it has a higher sugar content and isn't strictly a juice as it contains more fibre.  

Fasting for Women vs Men

Is Fasting Different for Guys and Girls? Short answer: Yes - and it’s important.

For women, hormones like oestrogen and progesterone are more sensitive to fasting. Long or aggressive fasts (like constantly skipping meals for days or weeks) can mess with your menstrual cycle or energy levels. Big dips in blood sugar can cause hormonal imbalance and ultimately make PMS symptoms, acne, cycle regularity and mood much worse. Fasting is not recommended for pregnant or breastfeeding women, as it can deprive the foetus or baby of essential nutrients.

For men, fasting tends to be easier on the body, hormonally speaking. Men aren't as affected by monthly hormonal changes as women and often men may be able to go longer periods of time without food than women. That doesn’t mean girls can’t fast - it just means moderation is key and do what feels right for your body.

If you’re a teen (of any gender), your body is still growing and developing, so extreme fasting isn’t recommended. But a short fast or a day-long juice cleanse once a month? Usually safe, as long as you’re listening to your body.

How Long Should You Fast?

If you're just getting started, don’t go all in with a 72-hour fast. You may want to try intermittent fasting or a one day juice cleanse first to see how you feel. 

Here’s a simple beginner’s guide:

• 12-hour fast ( 7 p.m. to 7 a.m.): Great for gut rest and better sleep.
• 16:8 intermittent fasting: You still eat your 3 meals a day but just in a shorter 8 hour window eg: 12 p.m. to 8 p.m.
• One-day juice cleanse (once a month): A gentle reset for your digestion.

The key is to start small, be consistent, and notice how your body responds.

Want to try a 3 day juice cleanse?

Once you have tested the water with a fast or 1 day  juice cleanse you might want to build up to a 3-5 day juice cleanse.  Many people experience a myriad of emotions on their first 3 day cleanse but after you’ve done it once you find it becomes much easier. 

Day 1: often feels ok. You may still have a buffer of energy from the foods you ate the previous day. 

Day 2: can often feel the hardest. You may feel tired or foggy-headed, grumpy or emotional and even hungrier than ever. This is part of your body going into a ‘detox’ phase. You may also be starting to head into ketosis where your body burns fat for energy, although this varies from person to person and can be anywhere from day 2-4.

Day 3: You may feel like you turn a corner on this day. You could be surprisingly clear-headed, light, or energetic and ready to extend your fast for another 1-2 days.

Nutritionist Tip: it's probably best to choose a time when you don't have a big work deadline, physical commitments, exams or a stressful life event coming up as you may find these harder to deal with when on a cleanse.

Can You Exercise While Fasting?

You can exercise while fasting - but it depends on what kind of workout you’re doing and how long you’ve been fasting.

• Light movement (like walking, yoga, or stretching): Totally fine, even on a juice cleanse.
• High-intensity workouts (like HIIT, heavy lifting, or sprinting): Best done when you’ve had some fuel in your system - unless you’re already used to fasted training.
• During longer fasts: Stick to low-impact activity. Don’t try to be a cardio hero.

If you start to feel dizzy, tired, or weak, that's your body telling you to slow down or eat something. Always listen to your body.

Final Thoughts: Should You Try It?

Fasting can be a powerful tool for improving your overall health and wellbeing. Whether you choose to incorporate a juice cleanse or try intermittent fasting, it's essential to listen to your body and adjust your approach accordingly. Remember to stay hydrated, listen to your hunger and fullness cues, and prioritise nutrient-dense foods during periods of eating.

Benefits of Fasting 

Fasting and cleansing are not a magic cure. It won’t replace balanced meals, sleep, or exercise. But when done right - like with a monthly juice cleanse, a 12-hour fast, or light intermittent fasting - it can:

• Give your gut a well earned break
• Help reduce bloating (from overeating and general poor food choices)
• Encourage more mindful eating (when you do start to eat again)
• Increase energy and focus (once your body adjusts to the fast)
• Help improve your skin through proper hydration
  

Important note: Talk to a doctor or nutritionist before doing any intense fasting, especially if you’re dealing with underlying health conditions or disordered eating.