I began thinking about intermittent fast (IF) a few weeks ago after becoming fascinated by Peter Attia’s (MD) ‘The Drive’ Podcast, where he discusses all things related to longevity and increasing one’s ‘health span’ which is staying disease free for longer, rather than living longer with a disease. I’ll discuss this difference on another blog, the focus of this blog is understanding the evidence for IF and why I’ve started doing it.
What is Intermittent Fasting?
IF is a very broad term and can mean not eating for as little as 16hrs, or as much as 3-5 days!! It’s quite simple, it’s just having more clearly defined periods of feeding, and fasting, rather than eating all the time. This confused me quite a lot because I was always told you want to have ~5 smaller meals throughout the day and initially I struggled to reconcile this with the theory behind IF. I haven’t yet been able to research this as much as I would like so the comparison of the evidence comes in another blog.
What are the benefits of IF?
As someone who eats, a lot.. this all sounded ridiculous to me, until I started reading up about the benefits and I was blown away. I just read through a review paper (which provides a broad overview of the evidence) on IF published (NOTE: The article is behind a paywall, but I cant send the PDF to anyone who wants it) in the the New England Journal of Medicine, one of the most prestigious medical journals. I was was amazed at the far-reaching benefits of IF, including:
- Reduced risk of cancer
- Improved metabolic profile lowering the risk of diabetes (or even reversing it),
- Lower blood pressure, heart rate, improved HDL (the good cholesterol), reduced LDL (the bad cholesterol)
- Decreased inflammation and molecular stress
- Increased BDNF, a key signalling molecule which is reduced in mental health conditions
- If IF couldn’t get any better, it also improves your gut microbiota, which is key for having a healthy gut.
These aren’t even all the benefits, but as you can see, IF seems to improve almost every aspect of health. So how and why does it work?
How does intermittent fasting work?
The in depth explanation is outlined in the figure above from the paper. The main benefits stem from this thing called autophagy, which is a fancy word for getting rid of cells you don’t need. Essentially what happens is that when fasting, your cells start to get rid of the parts of the cells which are damaged and recycling the parts which aren’t, whilst reducing overall protein building. Autophagy is a period where every cell in your body begins to get refined, like an essay which is being edited, the extra bits which aren’t helpful, or even damaging get removed. Autophagy is believed to be the reason for the many anti-cancer properties of IF, because the cells which are maladaptive (potential cancer cells) get removed in this process.
But wait! Does this mean I’m going to lose all of my muscle mass, or not be able to put on muscle?
Well, I was worried about that as well, but interestingly there is another strength of IF here and it comes about because you have this intensified block of feeding, which promotes a greater recovery (outlined in the figure above). It is during the periods of feeding where you turn back on all the things you switch off during the fasting, you get increased protein building, increased mitochondrial biogenesis increased glucose which all promote an enhanced level of cell growth and tissue remodeling. Essentially, you go through this period of building up during the feeding period, then you strip away all the parts which you aren’t essential and helpful during the fast.
So how do I start?
Well, I’ve justed started on the past few days so the jury is still out on how it goes in practice, but I’ve been using a free app called Zero (funnily enough with Peter Attia as the medical director) which starts you off on a 16:8 regimen, which means 16hrs fasting, and 8hrs feeding. What this looks like for me is finish eating by 8pm, and then start eating again at 12pm the next day. One thing I will say is tea has been an absolute godsend for increasing satiety and it hasn’t been much of struggle at all getting through to lunchtime on an empty stomach.
I’d recommend starting out with Zero on the 16:8 regimen and see how it goes! Fot me the benefits seem to far outweigh the risks, so i’m going to try it for at least a month and see how it impacts me, and I’ll be sure to write about my experiences as well.
If you do have any medical conditions I would also recommend seeing a dietician or GP before starting this as it can be quite a change and this is all just information not clinical advice.
Harrison Hansford 