Intro to Fasting
Today I’m hoping to fill in a few more gaps on fasting and time restricted eating for you. Firstly – a definition – “fasting” equates to going more than 24 hours without food, and “time restricted eating” is when you limit the food that you eat in a day to a window – of between 12 and 4 hours. There is also “intermittent fasting” and a “fasting mimicking diet“. These are related, but separate and need defining as well, which I’ll do in part two. For the purposes of speed reading I’m going to mostly just refer to them all as fasting.
All have been shown both in good science and in wide ranging anecdotal reports to be highly beneficial for weight loss, metabolic health (ie blood pressure, blood sugar/diabetes, inflammatory markers), and brain health. And potentially longevity – although this is hard to prove due to the mostly long nature of human life anyway.
I’ve had some amazing results with clients who have embraced either time restricted eating or fasting for weight loss. For years I wondered why it was that exercise and our “high carb diet” had little to no effect on weight loss. I watched Ironman competitors not lose an ounce. I’ve now realised that a combo of exercise and fasting is the easiest and healthiest way forward. Most people doing it will tell you that it’s not as hard as it sounds. The best way to begin is by starting to exercise your fasting muscles! It’s fairly easy to push breakfast out to 10am and gain your first benefit from that. Once you’ve done that for a week or so you might be ready to try stretching to lunch and getting that 18 or so hours of time restricted eating. From there to 24 hours (say 7pm to 7pm) is only a little harder.
Lots of the perceived difficulty is in our mentality of struggling with not having a meal to look forward to and the association of food with comfort. You’ll need to find your own mental sweet spot of getting through that; filling your day seems to help, as does remembering that you do have access to food anytime you need it – unlike some humans! Focus on planning your next meal and how good that will be, and the benefit that you’ll be getting in the time between.
A cool side effect of fasting is Autophagy. This is when your cells do their renewing. Old cells are replaced by young and better cells. Autophagy seems to happen best when the body isn’t doing much else – especially digesting. We also release brain fertiliser, known as Brain Derived Neurotrophic Factor, or BDNF, when fasting. This is released while exercising too! Your mental clarity is fascinating to see whilst fasting – you’ll find yourself powering through brain heavy tasks. Just like you do straight after exercise. People are often afraid that work will suffer during a fast – where in fact it will likely improve.
If you’re planning on trying out some fasting it’s a good idea to keep moving too – although don’t push yourself to crazy levels – just walk or do easy runs/rides, and just use body weight or do easy weight training until you are more accustomed to how it feels. A key ingredient to successful fasting is that you stay really well hydrated though. So if you are exercising double down on the water. It’s a good idea to add some electrolytes too – some say a pinch of salt will do the trick.
In up to 3 days of fasting (if you ever get to that point, which is starting to become somewhat mainstream) you won’t lose muscle, which is a much worried about side effect. Longer than this you probably will. And you will lose water weight – due to your food containing lots of extra water – but you should also begin to burn through some of your body fat reserves.
You shouldn’t fast if you are pregnant or breast feeding, if you are underweight/malnourished or have an eating disorder. If you have medical conditions and are on medication you should run it past your GP or specialist. If you have a very overweight child, some fasting managed through a specialist can be amazing, but otherwise children should not fast.
In NZ we have some of the best and most well researched/written scientists in the world on this topic. For great reading start with Grant Schofield and Caryn Zinn’s book “What the Fast”. I love listening to the Diet Doctor podcasts who advocate a low carb lifestyle as well, which goes in hand nicely with fasting. A company called Virta Health in the US is combining longitudinal research with coaching customers into better health by using fasting to reverse diabetes. And Canadian Dr Jason Fung is doing incredible work and worth following too. You don’t have to go far to find truckloads of fasting literature, so hopefully this inspires you into looking a little deeper.