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Intermittent Fasting - What is it and is it for you?

Weight managementDecember 15

Fasting for health? No way – isn’t that unsafe and damaging to your metabolism and weight loss?

Well actually, no. Recent research has found that there are many benefits to reducing our calorie intake from managing our weight, achieving fat loss, balancing our blood sugar levels, improving insulin sensitivity, stabilising energy, maintaining heart health, gaining mental clarity, inducing cellular repair mechanisms and perhaps even increasing longevity. The theory being that when we reduce our eating the body has more time to focus on clearing toxins and repairing and rebuilding tissues, rather than the energy demanding task of continually digesting food.

Different types of fasting have been studied, including zero calories for 24-72 hour periods, alternate day calorie reduction, reduced calories 2 days out of 7, long term calorie restriction and eating only over an 8 hour period (16 hours of fasting). Each of these methods produced different health benefits but needless to say some of the more extreme examples such as 72 hour fasts and long term calorie restriction struggled to get decent compliance when taken to the masses.

Intermittent fasting, which is essentially reducing your calorie intake to around 25% of your normal diet (or around 500 calories) on either alternate days or 2 non-consecutive days per week have been found to be easier to stick to over longer periods resulting in greater compliance with the programme. Even though these programmes are described as fasts which we naturally think of as abstaining from any food – you actually can eat a reasonable amount of food within the 500 calorie limit – providing you choose well which will also help you to avoid malnutrition.

It is thought that most of the benefits occur due to overall calorie reduction, meaning that non-fasting days must not become a free for all just because you fast 2-3 times per week. You still need to continue to make healthy food choices on non-fasting days and not become a glutton. Interestingly, when you fast for a period, be it 3 days in a row or intermittently, you become much more aware of your body’s hunger signals and therefore more inclined to eat only when you are actually hungry, not just for the sake of it.
This is obviously an important benefit for long term weight management and may be part of the mechanism behind restoring balance to the signalling of hunger hormones leptin and ghrelin.

    There are many different ideas about how to get the best benefits out of intermittent fasting; the most important factor is to make it a regime you can stick to. The following recommendations are for healthy individuals wanting to try it out.

  • Women eat 500 calories (2100kJ) and men eat 595 calories (2500kJ) on fasting days
  • Start by fasting 1 day per week for 2-3 weeks, then try adding in a second day with at least one non-fasting day in between (i.e. non-consecutive fasting days)
  • Aim to eat all food within an 8 hour period say 10.30am – 6.30pm leaving 16 hours of pure fasting
  • Include protein – it provides lasting energy and satiety without too many calories
  • Include some good fats – they are calorie dense so you will have to go easy on your fasting days, but be sure to have some
  • Load up on leafy green veges – they are low in calories and carbohydrates but provide plenty of filling fibre and essential vitamins and minerals
  • Eat at least 30g protein
  • Drink plenty of water – don’t confuse hunger with dehydration
  • Eat mindfully and free of distractions; take your time and savour every mouthful – this will help your brain to get the message that you’ve eaten

You will need to be cautious with regard to portion sizes and even weigh some food as you get used to what 500 calories a day looks like. While calorie counting is not something we typically endorse the extra effort for 1-2 days per week may provide some long lasting benefits.

Mercola, J ‘How Alternate-Day Fasting Can Help You Achieve Your Weight Loss Goals’. Accessed: 25 June 2014. http://articles.mercola.com/sites/articles/archive/2014/06/08/alternate-day-fasting.aspx

Barlass, Tim ‘Fasting Diet Gains Backing’. Accessed: 24 June 2014. http://www.smh.com.au/lifestyle/diet-and-fitness/fasting-diet-gains-backing-20130216-2ejtg.html#ixzz35WaZ6xjh

Goodyear, Paula ‘The fast track’. Accessed 24 June 2014. http://www.smh.com.au/lifestyle/diet-and-fitness/blogs/chew-on-this/the-fast-track-20131019-2vu18.html#ixzz35Welgnhm

Collier R, ‘Intermittent fasting: the next big weight loss fad’ Canadian Medical Association Journal, 2013 May 14, 185(8): E321-E322.

Collier R, ‘Intermittent fasting: the science of going without’ Canadian Medical Association Journal, 2013 June 11, 185(9): E363-E364.

Shepherd, Brad ‘The Benefits of Intermittent Fasting’. Accessed: 25 June 2014. http://draxe.com/intermittent-fasting-benefits/