What is intermittent fasting?

Intermittent fasting (IF) means restricting the amount of food you eat for a given period, followed by a period of normal eating. It is growing in popularity, among both fitness enthusiasts and the wider population, as a fat-loss tactic – but it is still controversial.

This is because it challenges many established beliefs, such as the importance of frequent eating and meal timing to prevent muscle breakdown. However, proponents of IF say it has multiple benefits, including improving body composition and reducing fat stores while increasing muscle mass.

How would I do it?

There are many ways in which people can approach IF. There’s the alternate-day fast, in which you restrict your calories every other day, a fast once in every seven days or a fast every third day. However, the one that’s achieved recent prominence is the 16-8 method, when you spend 16 hours a day fasting and the remaining eight hours feeding.

Does it work?

Research shows a variety of benefits of intermittent fasting. Studies conducted on animals have demonstrated increased lifespan thanks to fasting and calorie restriction. Studies have been done on humans too, but the findings aren’t as concrete. However, they are positive in that they demonstrate IF raises insulin sensitivity – which means your body is more efficient at processing nutrients – and lowers body-fat levels and blood pressure.

What are the disadvantages?

A serious problem for many, not surprisingly, is hunger. Going long periods between meals is something we in the developed world are unused to and research shows a higher meal frequency is better for maintaining feelings of fullness.

A bigger issue for those who train regularly is increased expenditure of muscle tissue for energy. Pre-workout carbohydrates and protein in the form of essential amino acids reduce the amount of muscle used for fuel, which would be higher when working out on an empty stomach.

Eating before training also increases protein synthesis, or the building of new muscle tissue, which is also helped by eating high-protein meals consistently through the day. Many IF protocols also preclude breakfast. Although this may be beneficial for fat loss, eating first thing in the morning has been shown to improve memory, concentration and food-choice discipline later in the day.

What are the advantages?

As well as improving your body’s ability to process nutrients through increased insulin sensitivity, IF has also been shown to reduce levels of body fat. It does have more practical advantages too – you don’t have to worry about preparing meals in advance to ensure you get the right nutrients, and it’ll probably save you money since you’ll be eating less overall.

So should I do it?

As with any nutrition goal, it really depends on your individual goals, physiology, preferences, lifestyle and a host of other factors. Research on IF demonstrates there both pros and cons associated with the approach. Besides, anyone who claims their nutritional methodology is the single best approach to fat loss is misguided – there are many ways to skin a cat.