Intermittent fasting – the pros & cons

The 5:2 diet,alternate day fasting, the 16/8 method, 24-hour fasts and the latest trending Debrow diet are just some of the popular diets that fall under the umbrella of intermittent fasting. Intermittent fasting or interval eating has recently gained lots of popularity in the health and fitness world and is fast gaining a cult like following. Before trying out any of these different fasting techniques, it is important to understand what intermittent fasting is and what effects (positive and negative) it has on our bodies.

Looking back to our hunter-gatherer ancestors, fasting would have been apart of their everyday lives as food was a scarce resource. Things are very different in today’s world as all types of food are available to us 24/7. Intermittent fasting has become a popular weight loss strategy as it reduces total energy (calorie and kJ) intake, and for some is a manageable way to control weight.

Lets have a look at the pros and cons of intermittent fasting:


  • Reduces total energy intake, helping with weight loss (you know the whole calories in vs. calories out scenario!)

  • Eating is somewhat inflammatory, therefore fasting may be beneficial in helping to reduce inflammation

  • Puts you in a fasted state which enhances fat loss as the body breaks down adipose tissue (fat) for energy

  • May speed up metabolism

  • May improve blood glucose regulation

  • Lowers insulin levels and increases insulin sensitivity which may reduce risk of type 2 diabetes

  • Can reduce LDL (‘bad’ cholesterol) levels

  • May be protective against obesity

  • Enhances cellular repair by stimulating the process of autophagy which may benefit general health and wellbeing


  • Fatigue and low energy

  • Can reduce sleep quality

  • May lead to nutrient deficiencies

  • There is often no guidance on what to eat during the ‘feeding’ periods

  • The 16/8 method or 24 hr fasts may interfere with daily activities due to the strict set eating times

  • May interfere with the social aspect of eating

  • Could be too restrictive for some and may lead to binging

  • May worsen digestive complaints

  • Loss of lean muscle mass if you are not consuming adequate protein

So as you can see intermittent fasting is not so straightforward! The take home message is that everybody is different and we all thrive off different ways of eating. What works best for you may not be what works best for your sibling, best friend or partner, and vice versa. There are many pros and cons when it comes to intermittent fasting, as well as lots of different fasting methods, and at the end of day you have to listen to your body and do what is best for you!

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