Intermittent fasting is a hot topic at the moment and for a good reason. It's something I recommend to certain clients in my practice and it can have extremely favourable health benefits such as weight loss, reduced risk of chronic diseases such as Type 2 diabetes and cardiovascular disease and increased brain function. Here is what you need to know about it.
Like a car, our body requires fuel to carry out its important functions; from walking to a heart beat. The primary sources of fuel is sugar in the blood (glucose) as well as stored sugar in the muscles (glycogen) and liver for later use. In the absence of these two sources, our body begins to breaks down fat stores for fuel.
When we are constantly eating, we are also constantly replenishing these sugar/fuel sources which means our fat cells stay fully loaded. As modern day life favours eating more food and moving less, these fat stores are bulking instead of breaking down, hence why obesity rates are rising.
Furthermore, digestion requires significant amounts of energy. When your body is trying to break down and absorb all the nutrients from food, other processes such as fighting off infections, detoxification, the removal of old cells (autophagy) and the regeneration of new cells are slowed down. Fasting allows the energy to be directed at your immune system and rejuvenation, helping your body fight disease and illness, ageing and eliminate dysfunctional, damaged cells to make room for new, healthy ones. Why do you think you lose your appetite when you are sick?
Here I answer the most frequently asked questions.
How long does it take until your body starts breaking down fat?
It takes on average 6-8 hours after you eat for your body to burn though the glucose and glycogen stored energy in the muscles. After that point your body will start burning fat as fuel. However this really becomes accelerated after 14 hours.
How does intermittent fasting work?
There are a few different ways you can structure your intermittent fast. A well-known one being the 5:2 structure whereby you eat normally for 5 days and fast for 2 days by eating under 500 calories.
An alternative and my preferred structure is the 16/8 hour method where you simply eat all your food in an 8 hour window and fast for 16 hours. This could mean you:
East breakfast later in the day e.g. Eat from 11am - 7pm
Skip breakfast completely and go straight to lunch e.g. Eat from 12pm - 8pm
Eat breakfast early and have your last meal early afternoon e.g. Eat from 8am - 4pm
The 16/8 hour structure is easier than the 5:2 structure because you are sleeping for most of the fast, it’s more flexible and you aren't required to eat less calories to see the effects of weight loss therefore aren't starving all day. You eat the same amount of food, you're just eating in a smaller time-frame.
Can you drink fluids during your fast?
Yes you can drink water, black coffee, and tea during your fasting period. They key is to drink lots and lots of water, especially when hunger starts to kick in. And keep busy!
Won’t Fasting cause muscle mass to break down, especially if I don’t fuel pre or post training?
Human growth hormone is a hormone that promotes growth, healing and repair of our cells. When insulin rises, this hormone is suppressed. In the fasted state, human growth hormone levels are at their peak which not only supports muscle growth but allows the body to clean up, repair and replenish damaged cells having healing and anti-ageing effects. This is why 8 hours of sleep per night is so important. Your body will only start to break down muscle as fuel after 72 hours. As long as you are eating a sufficient amount of protein during the 8 hour window, you won't lose your muscle mass. Furthermore, exercising in a fasted state, will force your body to burn fat as fuel.
What other health benefits are associated with intermittent fasting?
Improves insulin sensitivity so you can use carbs more efficiently as fuel. Effective for people with Type 2 Diabetes and insulin resistance.
Reduces sugar cravings
Increases brain function through the production of ketones – a type of fuel the brain can efficiently use
Lowers blood pressure
Boosts immune function
Is this way of eating for everyone?
No, this way of eating isn’t for everyone especially if you are pregnant, breastfeeding, hypoglycaemic or have a low body fat %. In these cases, fasting can stress your body and drive less favourable health effects. The key is to listen to your body and do what feels right for you.
Bear in mind, initially you might find it difficult as you are trying to train your body to become a fat burning machine. Give yourself two weeks and ease into it by fasting for 13 hours and work yourself slowly up to 16 hours.
Does it matter what you eat during your 8 hour eating window?
Of course. When it comes to good nutrition, quality is more important than quantity!
How many days a week should you fast?
I recommend starting off with 2-3 days and see how your body responds to it. It can take time for your body to get used to burning fat as fuel especially when you are used to eating 3 meals and 2 snacks a day. As you get better at it, increase your number of fast days. It's also a great tool to use when in need of a reset, especially when overindulging throughout this festive season.
If you are interested in learning more or having a tailored weight loss/fasting program written for you, Get In Touch!
Like using apps? Download the Zero Fasting Tracker app from the Apple store to track your fast.