What is Intermittent fasting?
Simply put, intermittent fasting is going through periods of time without eating (Fasting) then following this with an ‘eating window’. There are several types of intermittent fasting with the 3 most common types being:
· 16/8 (16 hours fasting, 8 hour eating window)
· 18/6 (18 hours fasting, 6 hour eating window)
· 20/4 (20 hours fasting, 4 hour eating window)
Beyond these there are more extreme types of fasting such as 24 hour, 48 hour, 72 hour and even 7 day fasts, these fasts are more extreme and while they do boast a pretty impressive list of potential benefits, they are definitely not something I would recommend starting without having thoroughly planned it through and consulted a doctor.
Additionally, it should be noted that most of the benefits come from the lack of food in the system, as such eating an enormous meal then fasting for 24 hours wont have the same benefits as a regular 24 hour fast, because it may take 12-14 hours for your body to work its way through all the food you have just consumed!
The 16/8 approach to intermittent fasting is the most common and easiest to implement, it is essentially missing breakfast! If you have your final meal at 9pm then your next meal will be at 1pm the next day. This approach works really well if you are one of them people who struggles to eat first thing in the morning, because you feel nauseas first thing after waking up or if you are someone who’s job requires getting up very early, then missing out breakfast could earn you an extra 30 minutes in bed. Which trust me as someone who has done plenty of work related 4am wake ups, that half hour does make a world of difference!
The 18/6 approach has most of the same health benefits as the 16/8 approach, but it just has a slightly longer period of fasting. If again you stopped eating at 9pm then your next meal would be 3pm. Essentially skipping breakfast and having a late lunch.
With the 20/4 approach we are starting to enter the ‘OMAD’ movement territory (OMAD stands for One Meal A Day), depending on the size of your meal a lot of people may only comfortably be able to fit one large meal in and some snacks during this 4 hour window. I have actually tried this approach and it works well and it feels amazing when it finally comes to the time to eat. BUT, it is really difficult to ensure you are getting all your micronutrients in when you are eating one meal a day and a few snacks. It is possible but you have to just be very mindful and aware of the foods you are choosing.
So what are the benefits:
· Changes to the function of cells
· Beneficial changes in gene expression which have been linked to longevity and disease prevention
· Cellular repair
· Initiates autophagy (basically the clearing out of old cells) this MAY provide protection against diseases such as Cancer and Alzheimer’s
· Higher levels of human growth hormone (higher levels of this hormone help with fat loss and muscle gain)
· Lower insulin levels (helps with fat burning)
· Short term increase to metabolism
· Lower insulin resistance reducing risk of type 2 diabetes
· Can reduce oxidative stress and inflammation
· MAY be beneficial for heart health (this benefit is a ‘may be’ because most of the research in this area has come from animal studies and these benefits don’t always translate directly over to humans.)
· Fasting can reduce side effects of chemotherapy (Definitely check with a doctor before trying though if this applies to you!)
· There may be benefits to the brain – animal studies (again bare in mind that studies on rats may not translate to humans but with the following benefits it’s definitely worth having a little think about) increased growth in the number of new nerve cells which should have benefits for brain function, increased levels of a hormone which a deficiency in can lead to depression, protection against brain damage from stroke (again these benefits were shown in animal trials but not human trials yet!)
· Could make you live longer (Once again a study on animals but still worth considering) a study on rats found that rats who fasted lived up to 83% longer than rats that didn’t!
There are two things to bare in mind with this final benefit; firstly, it was an animal study and there is no confirmation of this benefits for humans.
Secondly, the fasting may not have been the direct link it may be aspects which are a result of the fasting such as lower blood sugar, healthier lipid profile, lower body fat percentage and so on, so it may not be a matter of fast and you’ll live longer. It could be true that if you achieved these results doing a different diet you would get the same lifespan benefits!
So what’s the catch?
The first point isn’t really a catch it’s just a point which needs to be mentioned, Fasting isn’t an excuse to just eat whatever you want! If you fasted 20 hours, then ate 2 takeaway pizzas a milkshake and some ice cream and your total calories were 5,000 you would still gain weight! Fasting might have some benefits but it doesn’t remove you from the rule of more calories in than out = weight gain. More calories out than in = weight loss. Fasting doesn’t change this and this is where a lot of people go wrong. They will fast then as soon as it hits their eating window they will binge, not only will this mean you will receive hardly any of the benefits but this eating style is also very unhealthy from a dietary, physical and mental standpoint!
The next point that I want to make is that many of these benefits come either from studies which don’t specify the duration of fasting or use animals, and a 16 hour fast to a rat is a very different duration than 16 hours to a human (just look at the average lifespan of a rat, less than 2 years non domestic and 2-3 years domestic, and the average for a human, around 80 years, and you will understand what I mean!)
So given that our life expectancy is 40 times that of a rat it’s fairly safe to say that our 16 hours and their 16 hours is different. Using the ’40 times rule’ it would mean to match the rats 16 hours you would have to fast for around 27 days, to clarify I’m definitely not recommending this but it is worth pointing out that the studies can’t 100% be relied on.
So to conclude, intermittent fasting has loads of different benefits but as mentioned above how reliable some of these are, can be debated. So with this in mind I wouldn’t recommend choosing this diet because you think it is some possible life extending magic process, because there is every chance it isn’t!
However, it definitely does have benefits it can be an excellent weight management tool, it can help control blood sugar and it can help to build self discipline (but don’t become obsessive with it! This is a whole other issue and something to be very mindful of. Getting obsessed with either calorie counting or uncomfortably extending your fast is unhealthy mentally and physically!) The last point I want to make is this diet can be a point of comfort, if you start work really early and feel very sick when you wake up (which I know a lot of people struggle with) then this diet can massively help since you don’t force your body to eat breakfast when it isn’t ready for it! Each of our body clocks are slightly different and if yours is signalling nausea and a complete reluctance to eat food it probably wont thank you for forcing food into it!
I hope this information has been helpful and helps you decide which approach would suit you best if you are considering implementing intermittent fasting. As always if you have any questions just drop me a message!
Next week’s topic – The value of Sunshine!