Intermittent fasting has been slowly building popularity in the health and fitness industry alongside paleo, low carb and ketogenic diets, but when you the scrub away the faddy nature of any ‘diet’ that gets mainstream attention and begin to understand the science behind fasting, you can see why it can be such an effective method for fat loss. Read on to hear about my own personal experience and some simple guidelines to intermittent fasting.
What is fasting?
Simply put, fasting is an extended period of time without food. Obviously, this means longer than just a few hours between meals so a more accurate definition of this might be an extended period of time without food that allows the body to tap into internal reserves of fuel. We have a fed state where our body uses the fuel we directly receive from the food that we eat, and a fasted state where our body resorts to using fuel that we have stored up. It’s a pretty nifty mechanism and one that has kept humans alive since the Palaeolithic days when availability of food could be sparse.
Let’s take a closer look at the science and physiology of feeding and fasting.
Glucose and fat are the bodies two sources of fuel where glucose is the body’s immediate and default choice of fuel, and fat is the backup. So when glucose isn’t available our bodies draw energy from our fat reserves. When we eat carbohydrates it breaks down into glucose that travels through our bloodstream and gets shuttled into cells to be used as fuel. Glucose also gets stored away as glycogen into our muscles and the liver, that can be converted back to glucose for later use. When blood glucose and glycogen levels are both depleted i.e. during a fasted state, the body can then resort to using fat by creating ketones to be used as fuel in place of glucose.
By understanding this mechanism, you can see how fasting can be used as an effective method for fat loss. In addition, fasting allows our bodies to rest from the stress and inflammation that digesting food can bring. Reducing inflammation levels in the body can allow resources to be diverted to other systems in the body such as detoxification of harmful toxins, boosting immunity, and protecting the body from disease-causing free radicals. We actually fast overnight while we sleep giving our bodies time to rest, replenish, detoxify, grow, and heal, hence why the first meal of the day is called ‘breakfast’ as you break your evening fast. It seems obvious right but I bet you never thought of that until now.
There are various methods of fasting that range from:
I am going to discuss Intermittent Fasting as it I think it is the easiest method to incorporate into our lives without causing too much disruption and can be relatively well sustained. Typical fasting to feeding hours can be 16hrs:8hrs, 18hrs:6hrs, 20hrs:4hrs. While fasting for longer periods of time e.g greater than 24 hours, has shown to have greater benefits as the body is spending more time burning fat and is under less inflammatory stress, it can be a gruelling process and takes a lot of discipline. I have a couple of clients who celebrate Ramadan and dry fast from sunrise to sunset over a period of a month. It can typically result in having drastically lower energy levels and reduced productivity, and end up gaining weight during the process. This kind of extreme fasting when performed well can have huge benefits but it takes discipline both in the fasted and feeding periods.
If fasting is something you want to try adding into your daily routine I would recommend starting with a 16:8 intermittent fast and here are my tips on how to get the most out of it.
First of all let’s understand why 16hrs is a good place to start. We know that our body will start to burn fat as fuel once glucose and glycogen have been depleted. In fact, about 4hrs after we eat and glucose and glycogen levels are declining, the body is already getting ready to switch fuels and starts creating ketones from fat. The lower the glycogen levels drop the higher the ketone level rises until about 16hrs post feed, when all glycogen has been depleted and the body is solely using ketones. This is where fasting for greater than 16hrs can be more beneficial for fat loss though harder to do.
The majority of time spent fasted is while we sleep so 8hrs is taken care of. Typically, people will continue the fast into the morning and break around 12-1pm, as for a lot of people it is easier to skip or delay breakfast. This then gives a feeding window from 12-8pm or 1-9pm.
Isn’t skipping meals the same as fasting?
In short, yes and no. Yes, in that by skipping meals you are effectively lengthening the number of hours you spend in a fasted stated and shortening the fed state. But no, in that a) we still need to eat adequate amounts of calories during the shorter feeding window so we are only delaying when we eat, not cutting out a meal, and b) that fasting is a conscious act of abstaining from food, and thereby leading to the conscious and mindful act of feeding. That doesn’t sound like much of a distinction between them but stay with me. Skipping meals whether unintentionally like when we lose track of time, or intentionally perhaps in the effort to eat fewer calories to lose weight, can result in making poor dietary choices when the time comes to eat. The key difference here is that with conscious fasting and conscious feeding, the food choices you make will either help or hinder your fat loss goals. We all know what it’s like to go without food for too long. The hunger pangs, the food cravings, ‘hanger’ when we get hungry and angry etc, followed by the subsequent binge eating on junk food or foods that we subconsciously get drawn to to give us the quick boost of energy that we so need/desire.
To intermittent fast effectively we look to maximise our fasting and feeding windows and ensuring we are eating the right foods and of adequate amounts, to sustain energy levels and productivity.
I’ve had some great results these last few months intermittent fasting. I look and feel leaner, have more energy and vitality, have found discipline in our other areas of my life by having to stick to a routine, and have actually carved out more time in my day to be mindful, rest and relax. I have an even deeper appreciation of food and I get to eat the foods I enjoy while still losing bodyfat. For me it has definitely been an enjoyable process. My original intention was to do 1 full month of 16:8 and then see what happens. And although the first 2 weeks were a struggle while my body adapted to not eating first thing in the morning, after the month was complete I found it was so easy to continue.
Here are my tips on how to get the most out of intermittent fasting.
CHOOSE AN 8HR FEEDING WINDOW THAT WILL WORK FOR YOU. Commonly people choose to feed between 11am-7pm, 12-pm-8pm, 1pm-9pm as it can be easier to delay breakfast. It can also be good on a social level to eat dinner with friends and family, something that is important for wellbeing. However, our metabolism follows our circadian rhythms working at its peak between 10am-2pm, so eating too late into the evening isn’t ideal. So I find a feeding window of 9am-5pm or 10am to 6pm works best for me and my lifestyle.
BE FLEXIBLE WITH YOUR WINDOW. The time at which you break your fast isn’t as important as getting the number of hours of fasting in. Say for example your standard feeding hours are 12-8pm but you know you have a meeting the next day at 12 and won’t be able to eat until 1. You can either:
DURING THE FEEDING WINDOW
DURING THE FAST WINDOW
So there you have it. My simple guide to intermittent fasting. It does take some amount of discipline and lots of preparation, planning and timing. Cooking and bringing 3 packed lunches into work everyday and figuring out when I can eat around my client appointments, when to train, when to rest etc can require lots of organisation. But it's a routine that I'm very much comfortable with now and I really enjoy the process. If you want to give it a try yourself get in touch for extra advice or check out https://www.dietdoctor.com/intermittent-fasting for more information, resources and some great low carb recipes.