Is Fasting Fabulous?
Fasting has certainly become a “thing”, whereas it used to be something that people did more for spiritual or religious reasons.
Michael Mosleys 5:2 protocol (eat normally for five days a week, have very restricted food intake on the other two) certainly became popular, and nowadays having a time-restricted window for eating (8 hours within which to eat -not 8 hours continuous eating - and 16 hours fasted) also has many proponents.
So, is it good for you? Does it “work”? And, more importantly, does it work for women? Most of the research has been done - you guessed it - on men. Generally, overweight men needing to lose weight prior to surgery. Women are more complicated hormonally and metabolically, and we often need to approach things differently.
And we benefit from fasting in different ways depending on whether or not we still have a menstrual cycle. Fasting without regard to what our hormones are doing can be counterproductive. Whereas men can fast in all sorts of different ways depending on their aims, and the only thing they really need to do is avoid adaptive thermogeneses - that it is to say, they need to mix it up to avoid adapting and therefore getting less benefit.
When it comes to our digestive system, we have essentially two states: fasted, and fed.
Obviously, there’s a progression from fed to fasted - just after a big meal we are fed, and gradually we become less and less so, as the food moves through our digestive tract, until, about 4 hours after we eat, we are fasted. Obviously, if the meal was smaller, you will move into a fasted state more quickly.
Unless you wake up in the night and eat, chances are you are fasted when you wake up in the morning, hence break- fast, breaking your fast.
If you do wake up in the night so hungry that you need to eat, it is a sign that you are in metabolic disarray - or else, an elite athlete with almost no body fat. Assuming it’s the former, there is a lot you can do to improve your metabolic regulation.
It turns out that digesting food is a considerable demand on the body, and that it’s the fasted state that allows a load of essential functions to get done, which are outlined at the end of this article. Being in a continuously fed state interferes with this process, as well as playing havoc with our blood sugar regulation (although this depends a lot on what we are eating).
Remember, glucose is the body and brain’s fuel, and we need a nice stable supply of it. The issue is that (unlike horses and guinea pigs) we don’t eat all the time and so we need ways to even out the delivery system.
This is where the little and often approach is often suggested - rather than big meals, perhaps eating smaller meals more often can deliver nutrients and energy in a more steady way?
Guess what? This is one of those areas where there are huge differences of opinion, with some putting snacking in more or less the same category as smoking, and others denigrating the boa constrictor approach.
Of course, it depends what you are snacking (or mini-mealing) on, and it seems that different people respond differently to the different approaches, and that this can change over your lifetime, as well as with your current activity level.
It also depends to a very large extent on how much spare energy you have stored around your body. That is to say, do you have convenient fat deposits that could see you through a lengthy famine? Or are you like an engine, and the moment you run out of fuel, you run out of power? The Tour de France cyclists, for instance, keel over pretty fast if their glucose and electrolyte drink is replaced by plain water. Racing up mountains requires a lot of instant energy!!
Because the amount of sugar we can have circulating in our blood at any given moment is surprisingly small - ABOUT A TEASPOON!!! - we need to do something with the excess sugars we consume, if we aren’t an athlete using them straight away.
We can store some as glycogen in our muscles, ready for when we need it (and we can change how much we store there, which is part of the benefit of HIIT training), and also in our liver, but the rest will be converted into fat, where it is safely buffered away from our blood stream, but can be accessed and “burned” in times of need.
The difficulty lies in the fact that the body is quite happy with these reserves of energy being stored around the body, and won’t automatically turn to using them up. This is where people - especially women, and especially perimenopausal and menopausal women - find themselves “weight loss resistant”. That is to say, nothing (and particularly not the ol’ calorie deficit approach) works.
It turns out that one of the most effective ways to get the body to release some of its energy reserves is by fasting.
Another is to considerably lower the amount of carbohydrates - especially in the form of simple sugars - that we eat.
And the most effective way? Implement both at the same time. This might sound super challenging, but it’s actually easier to do it this way.
Let’s consider the two primary ways of fuelling the body.
One is carbohydrate based.
One is fat-based.
Our Western diet almost inevitably puts us into the first system. Carbohydrates like bread, pasta and rice tend to be the basis of most meals for a lot of people, and crisps, cakes biscuits and sweets are woven deep into our snacking culture.
Unfortunately, that mostly means playing havoc with our blood sugar and insulin levels, as these sugars are easily released from the foods we eat, and head straight into the blood stream. This can lead to insulin resistance and pre-diabetes, and a rollercoaster of energy spikes and crashes which we have already covered at some length!
Fasting can definitely be effective even if you don’t change your diet the rest of the time. But it’s harder to fast if you continue on that blood glucose rollercoaster, because you will likely be really quite hungry for quite a lot of the time that you are not eating.
The more carbohydrates you eat, the more carbohydrates you will want to eat, and the shorter the time between meals and snacks will tend to be.
If instead you consume more fat, more protein, and fewer carbs (and we’re not talking keto here, exactly, but definitely waaaay fewer carbs than the usual Western diet contains), your energy levels will remain much more stable, and you will consistently and steadily burn fat as the fuel, clearing consumed fats from your bloodstream and accessing stored fats as needed.
It’s an extraordinary feeling once you get used to it, as suddenly you feel much less hungry and have this nice stable, consistent energy. If you tried the 5:2 fasting regime before and found it didn’t work for you, you might find the 16:8 works much better. The problem with the 5:2 is that it doesn’t give you much time to really switch into the fat burning system, so you may find you are very hungry, or you have difficulty concentrating. Whereas when you extend your fast on a more regular basis (not every day forever, but several days in a row quite often), your body and brain get used to burning fat as fuel, and so it feels like really minimal hardship.
Reducing your stored energy reserves has enormous benefits in itself for your health, and potentially how you feel about yourself, depending on where you are at with that. But there are a whole host of additional benefits that accrue as a result of spending more time in the fasted state.
We will look at these in more detail below but for now one of the simplest things you can do is to extend your normal fasting window.
Pretty much *all* the advice points to not eating within 3-4 hours before going to bed (or at least if you do, just a small high protein snack) so eating dinner an hour or so earlier, and pushing breakfast back a bit can be immensely beneficial. You might find it easier to do it incrementally. So if you currently eat at 9pm at night and then again at 7am (10 hour fasting window) you could bring dinner forward to 8pm (11 hour fast), and then breakfast back to 8am (12 hour fast), and so on. Although as I say, integrating this into a routine allows the body to adapt somewhat, and so if it happens that some days you are in the office (and prefer to eat before you go in), and some days you are at home (so can more easily push back breakfast), you might do it that way. Sometimes you might have an evening commitment and can’t fit dinner in so very early, and perhaps you do have a small meal before you go out and a late, small meal when you get back. Even 12-13 hours of fasting has benefits, and at 17 hours you get into autophagy (see below).
Once you do break that fast, though, doing so with a meal rich in protein and fat, and lean on carbohydrates, will prevent an early spike and crash. It does seem that getting on that blood glucose rollercoaster early in the day makes it harder to get off it.
If you still have a menstrual cycle, there is some really interesting information in “Fast Like a Girl” by Mindy Pelz.
If you are post menopausal, you can also follow the same metabolic reset programme she outlines, or you can fast as and when it suits you - the important thing is not to stick to a strict routine, or to do it all the time.
What are those other benefits of fasting that I promised to explain?
We already talked about improved metabolic health, by enhancing insulin sensitivity, allowing cells to use glucose more effectively, which can reduce blood sugar levels and lower the risk of type 2 diabetes. Also fat loss - bearing in mind that belly fat in particular is “active fat” and can be metabolically and hormonally disruptive.
Other benefits:
Cellular Repair and Autophagy
Fasting triggers autophagy, a process where cells clean out damaged components, which may reduce the risk of various diseases, including cancer and neurodegenerative disorders. Exercise can also do this.
Cellular Repair: Fasting enhances the body's ability to repair damaged DNA and other cellular components, potentially reducing the risk of chronic diseases.
Reduced Inflammation
Fasting has been shown to reduce markers of inflammation, which is linked to many chronic diseases like heart disease, diabetes, cancer, and Alzheimer’s disease.
Heart Health
Cholesterol Levels: Fasting can lead to improvements in blood lipid profiles, including reductions in total cholesterol, LDL cholesterol, and triglycerides, which are risk factors for cardiovascular disease.
Blood Pressure: Some studies suggest that fasting can help lower blood pressure, further contributing to heart health.
Brain Health
Neuroprotection: Fasting may protect against neurodegenerative diseases by promoting the production of brain-derived neurotrophic factor (BDNF), which supports brain health. (Don’t forget, exercise, particularly resistance training, also promotes BDNF).
Mental Clarity: Many people report enhanced mental clarity and focus during fasting, likely due to the effects of ketones, a fuel produced from fat when glucose is scarce.
Longevity
Lifespan Extension: Some studies suggest that intermittent fasting or calorie restriction can extend lifespan, potentially due to its effects on metabolic health, autophagy, and reduced inflammation.
Hormonal Balance
Fasting can influence the secretion of hormones like insulin, leptin, and ghrelin, which regulate hunger, metabolism, and fat storage, contributing to better weight control and metabolic health. It also interacts with the female sex hormones, and can be used to help with cycle regulation and fertility, as well as PCOS.
Improved Digestion
Periods of fasting give the digestive system a break, potentially reducing bloating and improving gut health.
All in all, there are some very good reasons to consider adding fasting to your lifestyle, and many different ways of doing so.
It isn’t for everyone, and of course if disordered eating is something you are or have been struggling with, fasting may not be the best option.
Having said that, some people have reported that fasting has repaired their relationship to food, that it has taken them back to a real appreciation of their source of nourishment and what it does for them. Feasting is the other side of fasting, and some women say that just by increasing their fasting window and eating more freely in their "feasting" window, they feel a more naturla rhythm.
It's certainly worth considering.