Modern life is convenient with fridges, freezers, ovens – making cooking and eating a dance on roses. Life for our neanderthal ancestors was a tad less convenient. More often than not they only ate when food was available, thus fasting – intermittently (pretty sure you can see where we’re headed with this).
There are tons of different ways to fast, for example, by continuous fasting where you give yourself a really short eating window to consume your calories within a set amount of hours. A typical fasting period would be with a first meal at lunch and last meal at dinner, 13.00-18.00. Alternatively, you can do one or two full days in the week where you fast for 24 hours, it all depends on your general lifestyle and what suits you best.
However, for best results you need to fast according to your circadian rhythm (sleeping patterns, natural feeding times and all that stuff your body does and wants without you knowing about it). Doing this type of fasting does not necessarily mean cutting your calories, unless a weight loss is what you’re after, it simply means condensing your calories into your eating window. If you decide on an eating window of 8 hours, that really only means 16 hours of fasting, of which you really should be sleeping 8 of those hours, which is pretty doable irrespective of busy work schedules, picking up kids from school and exercising.
Scientists agree on three main benefits to your health by fasting; reduced oxidative stress, increased insulin sensitivity and mitochondrial energy efficiency and increased capacity to resists stress, disease and aging. Fasting is, of course, initially a stress factor to your body but when it responds to that stress on a regular basis it gets better at dealing with this and other stress sources.
Although some animals are savvy enough to store food, think big cheeked squirrels and woodpeckers, they rely entirely on the seasons, on the availability of their own legs, beaks, paws to catch the food they need. From an evolutionary perspective, it makes sense to fast – to not be restricted by scheduled meals on the same time every day (although some far apart snacking was probably involved, berries, nuts, leaves – all that yummy stuff). Life would’ve been a lot more unpredictable and as much as we’d like to think we’ve changed, we really haven’t, for better or worse.
Exercising while fasting
Our ancestors would have wandered for days scavenging for food, so moving about with only a half full stomach will not harm you. As mentioned, we haven’t come that far. Our activity rates have gone down massively alongside the convenience of modern food storage. This is better compatible with our actual physiology, which developed to move about (think swinging apes) and eat whenever food was available, not snacking every two hours. Athletes are encouraged to not fast for too long. Of course, extreme exercise should perhaps not be combined with a calorific deficit or on the days you do 24h fasts, should you choose that route – as it will put strain on your body after a long period of time.
It’s just breaking the fast
As a breakfast lobbyist, suggesting fasting as healthy might seem contradictory, but, and there’s a big linguistic ‘but’, there seems to be this understanding that breakfast need to be in the AM of the day (preferably before noon for most people before evolving into brunch). The word breakfast derives from breaking your fast, so technically your first meal of the day will always be your breakfast, irrespective of the time you eat it. It’s a very free concept that does not bind us to any particular meal or time.