To fast or not to fast . . .

If intermittent fasting was a superhero,
it would claim that its powers were:
​

• Superior fat ‘burning’,
• Increasing lean muscle mass
• Improving insulin sensitivity
• Reducing ‘inflammation’.

In other words,
It would claim to transform people to their desired shape.

I’m interested in learning more about the science behind intermittent fasting and if it is sustainable in the long term.  

What is intermittent fasting?

Basically, it means changing the timing of your meals and snacks so there is a prolonged period that you are not eating or drinking.
This is thought to help your body switch from a ‘fed’ to a ‘fasted’ state. This fasted state is thought to tell your body to utilise your fat stores rather than your glucose stores (glycogen) to fuel your body.  
There are many variations of fasting, a simple google search will prove this. ‘The 5:2 diet’ involves restricting calorie intake to 500-600 for two days of the week. The 16:8 fasting method involves a 16 hour fast and 8 hour eating window. The list goes on.

Let’s talk Science

Carbohydrate, or glucose, is the bodies preferred fuel source and one of the main objectives is to keep our blood sugar levels within a ‘normal’ range.
Our carbohydrate (glycogen) stores are depleted during exercise or if no food is consumed in 18-24 hours. Once this happens our body needs to find a way to produce glucose. Our bodies are so smart that they can break down our muscles to produce glucose, this is called gluconeogenesis. Our bodies can also utilise our fat stores in a process called beta-oxidation. Our fat stores are not converted to glucose but to ketones which can fuel our brain and muscle cells in the absence of glucose.
This happens when we are in the fasting state or “starvation” mode.  So, if we starve or fast, our bodies will use muscles and/or fat stores to keep us alive.
 
So, in theory, fasting may help utilise your fat stores, but in order to recommend fasting I need some scientific support that has been conducted on humans.
Unfortunately, much of the literature I have reviewed on this topic is based on anecdotal personal accounts, or laboratory studies on mice rather than human subjects.
The anecdotal evidence has presented individual accounts of people having had short-term success meeting certain weight management goals, but I have concerns about some secondary aspects of intermittent fasting.

 The issues I have with fasting:

Diets don’t work, we need to be able to continue the changes we make for the rest of our lives. This means fuelling our bodies and our minds.
I would argue that the psychological aspects of fasting (that is food deprivation/starvation) are not suitable or realistic in the long-term. They’re almost like a punishment.
We have different triggers to eat - environmental cues (like a morning tea shout), emotional cues (like sadness), stress, hormonal fluctuations, social events, exercise and our actual hunger cues.
I encourage people to identify what is triggering them to eat or overeat, understand why and then address that.  

 I also work with a lot of athletes. A sustained calorie restriction in athletes can not only impair performance and recovery, it can result in a condition called Relative Energy Deficiency in sport (RED-S) which can negatively affect bone health, hormonal balance, immunity, mental health and heart health.

 So, is Intermittent Fasting a Superhero? At this point I’m going to say no. That applies especially to those wanting to create a healthy lifestyle for themselves or their families or to meet nutritional requirements for exercise.

Reducing our intakes of processed foods, eating plenty of vegetables, oily fish, wholegrains and legumes are a way to fuel our minds and bodies. Actual food is the real Superhero.