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Intermittent Fasting

Intermittent fasting

Intermittent fasting (IF) may be one of the easiest ways to manage your health without the need to learn new cooking methods or rigorously read labels. With IF you can include small changes which, if done safely and correctly, could result in many health benefits including a slimmer waistline. And tell me who doesn’t want that except Barbie and Ken?

What is it?

Intermittent fasting (IF) is very trendy right now. And chances are, many of you are probably doing it already and some may be doing it without even realising. The many reported health benefits, and the ease of incorporating it into your lifestyle, has made it the world’s most popular health trend.

Simply put, IF is an eating pattern where people go extended periods of time without food, followed by periods of normal food consumption.

Health benefits

Flipping the body’s switch from a fed state, to a fast state, has many benefits. The New England Journal of Medicine found that IF not only reduces weight, improved metabolism, and reduced the inflammation associated with conditions such as arthritis and asthma.

When we are in a “fed state” our body is concentrating on digestion, but when we have finished digesting, our bodies can focus on other tasks such as clearing out toxic waste and mopping up the damaged cells associated with ill health. Can you clean your house and eat a meal at the same time?

Furthermore, preclinical animal trials have linked IF with the ability to modify a range of chronic disorders including; diabetes, obesity, cardiovascular disease, and neurogenerative disorders like Alzheimer’s and dementia.

Types of fasting

Ø 16/8 – fasting for 16 hours, eating for 8 hours between 12-8pm. It is generally recommended that women should fast for slightly less 14-15 hours

Ø 5:2 diet – In this IF you eat normally for 5 days a week and include 2 days of calorie restriction of 500-600 calories. For example: you eat normally every day of the week except Monday and Friday where you limit your calories to 500 for a woman and 600 for a man. Your fast days can also be done on two consecutive days

Ø 800 calorie diet – this is a follow on from the 5:2 developed by Micheal Molsey. This is an intensive program to weight loss that comes with a medical disclaimer

Ø Alternate day fasting or 4/3. This is where one day you fast, followed by one day of eating normally. Some varieties of these diets allow 500 calories a day

Ø Spontaneous meal skipping - listening to your body and skipping a few meals a week when you are not hungry

Ø Eat, stop, eat – fasting for 24 hours from dinner to dinner twice a week. Similar to the 5:2

What happens when you fast?

When you dramatically reduce between 500-700 calories a day, the body switches from using glucose as fuel, to using fatty acids and ketone bodies. These clever ketones are not only used as fuel, but they also tell the body to alter the expression of molecules in the body that regulate health and longevity. Research also shows that all organ systems in our body seem to respond well to repeated intermittent fasting, with our cells showing improved functions and increased resilience to stressors

Is it for you?

Fasting is not for everyone. There is some evidence showing that women benefit less from fasting than men (sorry ladies). There are studies showing that while fasting resulted in positive insulin levels in men, women had worse blood sugar control. And in animal models it resulted in skipped periods, emaciation, muscularisation and infertility in female rats.

While evidence suggests fasting has an excellent safety profile, you should definitely not consider fasting if you are pregnant, have a history of disordered eating, and must check in with your health practitioner before commencing any new diet/fasting regime.

And remember, no diet replaces good healthy eating and exercise. So, make choices that will serve your mind and body so that you go forward feeling nourished.

Written by Storm Sommerville

Adv. Dip Nutrition, Naturopthy, Herbal Medicine

Insta: Storm.Sommerville.Naturopath


1. The Obesity Code, by Jason Fung, MD (Greystone Books, 2016).

2. Dr Michael Mosley’s, Eat, Fast, Live longer The fast diet

3. The Fast 800: Michael Mosley

4. The Fast diet, Michael Mosley

5. 5:2 Diet Cook Book, Jacqueline Whiteheart


1. de Cabo, R., & Mattson, M. P. (2019). Effects of intermittent fasting on health, aging, and disease. New England Journal of Medicine, 381(26), 2541-2551.

2. Horne, B, Muhlestein, J. B, Anderson, J.L. (2015)Health effects of intermittent fasting: hormesis or harm? A systematic review, The American Journal of Clinical Nutrition, 102(2), 464–470,

3. Mattson, M. P., Longo, V. D., & Harvie, M. (2017). Impact of intermittent fasting on health and disease processes. Ageing research reviews, 39, 46-58.

4. Gunners, K (2020), Six popular ways to do intermittent fasting, Healthline, retrieved from

5. Heilbronn, L. K., Civitarese, A. E., Bogacka, I., Smith, S. R., Hulver, M., & Ravussin, E. (2005). Glucose tolerance and skeletal muscle gene expression in response to alternate day fasting. Obesity research, 13(3), 574–581.

6. Martin, B., Pearson, M., Kebejian, L., Golden, E., Keselman, A., Bender, M., Carlson, O., Egan, J., Ladenheim, B., Cadet, J. L., Becker, K. G., Wood, W., Duffy, K., Vinayakumar, P., Maudsley, S., & Mattson, M. P. (2007). Sex-dependent metabolic, neuroendocrine, and cognitive responses to dietary energy restriction and excess. Endocrinology, 148(9), 4318–4333.


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