Is intermittent fasting safe for you?

You may have noticed by now that there are a few things in the nutrition world that get us excited. Coffee is one. Intermittent fasting (IF) is another. But IF is not for everyone and is not effective unless it’s done properly.

Read on to find out if IF is right for you. 

What is IF?

Intermittent fasting is a term for eating patterns that cycle between a period of fasting and non-fasting during a specific period. There are several ways to implement an IF regimen, including:

  • 5:2 protocol
  • 16:8 time restricted eating
  • 24 hour fast

For more info on these fasting routines, visit

IF can provide great health benefits if implemented wisely and with support and monitoring
from a trained health professional. It can assist with weight loss while preserving our muscle mass and has been linked to longevity and reduced risk of some chronic diseases, including diabetes, cardiovascular disease and cancer.

If done poorly, not only can IF be ineffective, it can be quite dangerous.

Safety always come first. Then teamwork. Read on for our top 10 tips for fasting safely.

1. Get your baseline diet right first

It’s important to have a steady hand on a well-balanced, wholefood-based diet before contemplating starting IF. This can be the real key to success. Elise and I will always make sure your baseline diet is nutritionally sound and sufficient to meet your macro- and micro-nutrient needs before suggesting an IF routine. Make sure you chat to us first and set yourself up for success!

2. Keep fasting periods short

Don’t be a hero, and don’t set yourself up to fail. Fasting is hard and we all know what hangry feels like. Be realistic with the style of fasting that suits you and your lifestyle, and ease your way in. For example, if you’re working towards a 16 hour fast (including overnight), start with 12 hours, then try for 14 and you’ll feel much more in control when you reach the sweet spot!

Most people find a 24 hour fast is unrealistic and we agree. It’s our least favourite style and not for the faint-hearted. The longer the period of fasting, the increased risk of issues such as dehydration, irritability (AKA hanger), mood changes, fainting and reduced energy and concentration. We encourage anyone game to strive for 24hr fasting to speak to us or their doctor first.

3. Stay hydrated

Avoid dehydration by making sure you meet your fluid requirements. We get 20-30% of our fluid needs from food so we’ve gotta fill the void!

Our daily fluid guide is provided below and if you want an accurate measure tailored to you, hit us up!

Body weight (kg) Fluid needs per day
50 1.8L
60 2.1L
70 2.5L
80 2.8L
90 3.2L
100 3.5L

Fluids allowed during most fasts include:

  • Water
  • Black coffee (no sugar)
  • Black or herbal tea
  • Plain soda or mineral water

Bonus: drinking will help fill in the time so your fast doesn’t draaaaaaag as long!

4. Distract yourself

Avoiding food is hard. We love food. We want and we neeeeed food. But we can survive without it during our fast. We can’t all be like Ghandi and it’s okay to make it easier for yourself. In fact we wholeheartedly encourage it.

Some ideas of how to take your mind off that rumbling tummy…

  • Go for a walk
  • Meditate
  • Read or listen to a podcast
  • Have a bath – ooh la la!
  • Get social – makes plans with friends intentionally when you know you’ll’ be fasting. Just don’t meet at a cafe!

5. Easy there tiger. Avoid the end-of-fast-feast!

This can be the undoing of a successful fast and one of the reasons that we may recommend against IF. You need to have your baseline diet balanced. *Refer to point 1*  

While it can be tempting to eat the entire fridge after your incredible fasting effort (and yes, we’re so proud of you for making it!), try not to undo all your excellent achievements.  Not only can this leave you feeling bloated and fatigued and reduce the likelihood of weight and health benefits, the self-efficacy you gain from reaching your goal can quickly wear off if you lose your sense of control with meal 1.

The good news is we’ve got a foolproof guide to your first meal back after a fast! Find it here!

6. Know when to stop.

Don’t overdo it. You know your body better than anyone and if something feels NQR, stop your fast.

It’s normal to feel a little tired or hungry during your fast, but you should never feel unwell. Signs you should stop your fast and seek medical attention include tiredness or weakness that stops you from carrying out your usual daily activities or unexpected feelings of sickness or discomfort.

Keep fasting periods short when first starting out and ensure you have food and fluids available just in case.

7. Meet your protein needs

One of the great benefits of IF is that it can promote fat loss while preserving our muscle mass. In order to achieve this, it’s important to fuel your body with enough protein.

Include quality sources of protein on your non-fast days including:

  • Fish, poultry, meat, seafood
  • Eggs
  • Tofu and tempeh
  • Wholegrains, nuts and seeds (quinoa, chia, freekeh)
  • Legumes, beans and pulses
  • Dairy products (milk, yoghurt, kefir, cheese)
  • Speak to your OnCore dietitian about supplements

Protein can also help to keep our hunger in check so it’s extra important that your getting enough leading up to a fast!

If you have specific dietary needs or you’re keen for more detailed advice on how much protein you need, make a time to chat to us today!

8. Make sure you’re meeting your nutritional needs

Fasting ofen means we’re cutting out meals and this can leave us vulnerable to nutritional inadequacies. Deficiencies in iron, calcium and vitamin B12 are common when we change our diet.  It’s important to include a balanced, whole-food based diet when you’re not fasting, including a range of vegetables, fruits, grains and legumes, meat, poultry, seafood and dairy products. Our gut bacteria still need a good feed and so do all of our bodily systems.

If you’re concerned you’re not meeting your nutritional needs (including vitamins, minerals and phytonutrients) with your fasting routine, make sure you speak to us about the need for specific nutritional supplements.

9. Exercise within your limits

Be aware that, regardless of what exercise you do, you body may be running on empty. We kinda want it to be! Get into those fat stores for fuel please!

Some people find they’re able to exercise without any change when fasting. I actually find it helps pass the time! It’s important to listen to your body and when first starting out be sure to keep the intensity low – think yoga, walks, stretching, gardening – and see how you manage.

10. Fasting is not for everyone

And that someone could be you. If it’s not for you, don’t force it. There are plenty of other strategies we can employ to help you reach your health goals!

Fasting for short periods is generally considered safe but guidance from a health professional is always recommended. Some groups who should not attempt IF without medical consultation include:

  • Those with medical conditions such as cancer, low blood pressure, cardiovascular disease or diabetes (or anyone with difficulty maintaining blood glucose levels, especially if taking insulin), or anyone taking prescribed medications.
  • Pregnant or breastfeeding women, or women trying to conceive
  • People who are underweight
  • Anyone who has experienced disordered eating patterns
  • Woman with a history of amenorrhea (the absence of menstruation)
  • Older adults
  • Adolescents or growing children

In Summary

Intermittent Fasting can be a powerful tool for our health and longevity but it’s not for the faint hearted and certainly not for everyone. Don’t be a hero (or try to be Ghandi!) when fasting – if in doubt, eat something and seek guidance from us or your doctor.

T A I L O R  Y O U R  P L A T E   |   B U I L D  Y O U R  B E S T  Y O U 

Lauren Atkins

Accredited Practising Dietitian

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