Intermittent Fasting (IF) is one of the hottest trends hitting the health and fitness scene at the moment. There is a huge amount of interest in it’s application and benefits, so let’s take a closer look at these and hopefully answer some of the questions you might have around this topic!
What is Intermittent Fasting?
IF is a term that refers to an eating regime which cycles through periods of eating and fasting. This pattern of eating is more about ‘when’ to eat, rather than ‘what’ to eat. Ultimately, throughout the fasting periods, calories or energy intake is restricted, resulting in an overall caloric deficit.
The main types of IF that have been studied are:
Whole Day Fasting – one to two 24 hour fasting periods per week
Alternate Day Fasting – one day of fasting followed by one day of feeding
Time Restricted Fasting – fasting for a period of 16-20 hours every day (this is the most common form of fasting I have encountered in my clinic, possibly because it is the easiest to implement).
What are the benefits of eating like this?
Most people who undertake this pattern of eating are looking to lose weight; and it works! Because it is an energy restricted diet. Research shows that it is no more effective than any other energy restricted diet for weight loss, however some people may find it more convenient. Due to the periods of fasting, there is generally no need to count calories or monitor intake during the eating periods, as the amount of energy consumed does not completely account for the amount missed during the fasting period.
Studies also show that IF is no more beneficial that other energy restricted diet for improving insulin sensitivity/glucose control (this information comes from a systematic review of the evidence – some studies support this while other do not).
There are lots of studies that are showing a potential benefit of IF for prevention of chronic disease so watch this space, because the science is always evolving.
IF could be suitable for an active individual or recreational athlete if it was properly planned around their activity. There can be some benefits from training in a fasted state (particularly in endurance training). Periods of fasting can assist people in becoming more ‘fat adapted’, or being able to use fat as fuel more effectively. This has not been shown to provide a performance benefit but could be useful in endurance or ultra-endurance training.
If weight loss is your goal, then training while fasting can purely result in a larger energy deficit, which could potentially give you better results. There are some considerations to this though. If you are training fasting and performing poorly in your session, you need to consider if it is worthwhile. Also, if you are training fasted but are so hungry that you eat double the amount of food during your eating window, you may need consider another eating pattern.
In conclusion, IF is just one option, in a pool of many, that can assist with weight loss and improve your risk of developing chronic disease. Getting personalised nutrition advice can help you to determine the most effective eating regime for you.