Hippocrates recommended fasting as a treatment for a wide range of ailments, and he wasn’t the first. In fact, fasting has featured in our history books since as far back as the 5th-century BCE, and has especially been used within a religious context through festivals like Ramadan, which aim to help individuals towards self-improvements and spiritual enlightenment.
More recently, intermittent fasting has been adopted for its health and personal benefits. Frontrunners like Michelle Harvie and Mark Mattson have especially brought intermittent fasting into public consciousness, making it a popular menu item for many individuals looking to enjoy a wide range of benefits. Whether you’re interested in attempting intermittent fasting yourself, or are simply curious about this interesting dietary choice, this intermittent fasting guide will cover the how, what, and why of this eating pattern, providing you with the tools you need to get stuck in and see real results from your efforts.
What is intermittent fasting?
Unlike traditional, and typically unsuccessful, diets, intermittent fasting is best thought of as a kind of eating pattern that’s all about when you eat, rather than what you’re eating. While there are variations (as we’ll discuss below,) a typical intermittent fasting regime might involve fasting for as long as 24-hours around twice a week.
This can seem like an outlandish option for someone who’s used to consuming 3-4 meals a day, but the backing for intermittent fasting is very much based on fact and verifiable research, and studies actually tend to suggest that this may be a more natural way of eating than consuming large meals daily.
We’ll discuss the specific benefits of fasting in this manner below, but according to Mark Mattson, a fore founder of the intermittent fasting movement, success in this area stems from our hunter-gatherer ancestors, who would often go days without food. Mattson’s 25-years of study have led him to believe that our bodies have evolved to go without food for several days or longer. What’s more, Mattson states that, ancestrally, we would never have stayed up late enough for late-night snacking, and the weight gain this can bring.
Experts believe that it’s these less natural eating habits that are fuelling issues like obesity, which now impacts 13% of the population, type 2 diabetes, and heart disease. By taking us back to our ancestral roots, intermittent fasting aims to directly address these modern-day ailments. In this intermittent fasting 101, we’ll help you to get on top of the benefits that this eating pattern stands to bring to your life and mindset.
How does intermittent fasting work?
According to Mattson, “If someone is eating three meals a day, plus snacks, and they’re not exercising, then every time they eat, they’re running on those calories and not burning their fat stores.” As such, on a fundamental level, intermittent fasting works by withholding calories and prolonging periods during which your body burns only fat reserves. This is something that Mattson refers to as ‘metabolic switching,’ and is the foundation on which fasting-based benefits sit.
But, that’s an incredibly simplistic way to consider an eating pattern that is, in many ways, quite complex. On a hormonal level, especially, fasting facilitates significant shifts that ensure fat stores are more easily accessible meaning that, far from simply burning fat during fasting periods, long-term benefits are also on the table. Cellular changes also occur off the back of even brief periods of fasting, and these, alongside hormonal shifts, can lead to significant beneficial changes within the body, including –
- Increases in human growth hormone (HGH) - HGH is produced by the pituitary gland and helps to maintain, build and repair healthy tissue around the body, while low levels have been linked to obesity and a generally increased risk of disease. As such, increasing HGH brings a wide range of health benefits, and studies consistently show that fasting can make that happen, with one 1982 study, in particular finding that fasting for three days increased HGH by 300%, while a week-long fast led to an astonishing 1,250% increase.
- Cellular repair - Studies also reveal that fasting can initiate a cellular repair process known as autophagy, where cells digest and remove dysfunctional proteins that can sometimes be attributed to neurodegenerative diseases like Alzheimer's. Autophagy also encourages the regeneration of healthy cells, which keep the body younger and better able to fight disease, etc.
- Lower insulin levels - Around 8 to 12 hours after your last meal, you enter what’s known as a ‘fasted state,’ which allows your body to burn fat that was previously unavailable. This is because fasting also decreases insulin levels in the body, making stored fat more accessible, and thus facilitating weight loss.
- Increase release of norepinephrine - Fasting also increases the release of norepinephrine in the body, a hormone that directly relates to burning fat in the body, ensuring that the fat stores made available when insulin lowers are easier to break down.
Each of these benefits, alongside potential links to changes in gene function that can help to prevent brain deterioration or even cancer, fuel the health and weight loss benefits that fasting brings to the table. Intermittent fasting provides a quick and accessible way for even keen eaters to access these benefits without having to actively change what they eat when no longer fasting.
The benefits of intermittent fasting
Intermittent fasting is linked to a wide range of benefits, hence why fasting habits have such a strong place in our cultural history. From Hippocrates through to modern-day dieters – the benefits have long spoken for themselves. But, if you’re just now starting to consider intermittent fasting, it’s important to ask - what benefits can you actually expect to see from your efforts here?
- Weight loss - A 2014 study is just one of the latest to find that intermittent fasting can facilitate 3-8% weight loss over as little as four weeks. In some respects, this is due to a reduction of calorie intake, especially considering that those who binge after fasting fail to feel these benefits. That said, the hormonal changes mentioned in the previous section also play a significant role here, and are largely where long-term weight loss benefits lie. Notably, increases in norepinephrine and decreases in insulin work together to burn fat stores, facilitating Matson’s theory of ‘metabolic switching.’ The ease with which intermittent fasting can be implemented is another significant factor in this sense, preventing the need to get to grips with sometimes complex dietary eating plans that we all too often stray from. Rather, weight loss is possible here through inaction alone, driving the way for reliable results at last.
- Extended lifespan - Studies dating as far back as the 40s have suggested links between fasting and longer lifespans. More recently, studies have also pointed towards the fact that restricting calorie intake to 60-70% of normal adult requirements can prolong lifespan 30-50%. In some sense, you could say that this is because of the wider disease-fighting benefits of fasting, but from a lifespan perspective, in particular, the cellular changes mentioned provide an adaptive stress response that causes the body to go into attack mode, thus preserving life, and keeping cells healthier for longer.
- Lower risk of type 2 diabetes - As well as lowering levels of insulin in the body, intermittent fasting can also reduce insulin resistance, which ultimately lowers blood sugar by as much as 3-6%. This can drastically reduce the risks of type 2 diabetes, especially if intermittent fasting is implemented for extended periods. Furthermore, studies have shown that combining Intermittent fasting with a ketogenic diet can potentially be an effective way to treat Type 2 diabetes. https://pubmed.ncbi.nlm.nih.gov/32641437/
- Brain benefits - Intermittent fasting also improves various metabolic features that are important for brain health, including oxidative stress, reduced inflammation, and lower blood sugar levels. What’s more, fasting facilitates the production of the brain hormone, brain-derived neurotrophic factor (BDNF), low levels of which have been linked to issues including depression and anxiety.
These are the things we know for sure, but studies are very much ongoing in this area, and benefits continue to emerge, especially in areas such as disease resistance. Most notably in recent years, studies have shown potential links between fasting and cancer treatment, with a study of 10 cancer patients showing a strong correlation between fasting and the prevention of negative effects from chemotherapy. Further studies have also revealed a potential for improved heart health off the back of periods of intermittent fasting. One thing’s sure from what we do know – your health and your waistline will thank you for your efforts here.
Types of intermittent fasting
Intermittent fasting provides undeniable benefits, but it’s also vital to note that you need to do your research before you jump into a potentially dangerous or unhelpful fasting plan. Obviously, the best way to get started with an extreme physical change like this is to talk to your doctor, who will be able to advise you on a tailored plan that’s undertaken with professional supervision.
All of that said, a few key intermittent fasting plans are doing the rounds right now. Each of these involves splitting the week into eating and fasting periods, but they do vary slightly in terms of approach. The options you may want to consider include –
- The 16/8 method: First popularised by fitness expert Martin Berkhan, the 16/8 method (also known as Leangains protocol) involves a 16 hour fast followed by 8 hours in which eating is permitted. This 8-hour eating window can be at any time you prefer, though most users tend to skip breakfast so that they can implement their sleep routine within their fasting period. This is a fantastic starting point for intermittent fasting thanks to short fasting bursts and an eating window that still largely makes room for two-three meals each day. Some people will then move to 18/6 for a longer fast period.
- Eat-stop-eat: Brad Pilon developed the eat-stop-eat method which focuses on fasting for 24-hour periods over at least two non-consecutive days a week. Participants are then free to eat as normal on their non-fasting days, making this a popular option for those who prefer uninterrupted treat days between their fasting efforts.
- The 5:2 diet: Championed by British journalist Michael Mosley, the 5:2 diet involves eating regularly for five days of the week, and then limiting calorie intake to one 500-600 calorie meal for the remaining two days, as long as these are non-consecutive. This is a popular option in modern culture thanks to the limited periods of fasting involved, especially considering that there’s no research to suggest these shorter fasting periods are any less effective than entire 24-hour stretches.
Fasting safely: what can you consume
As touched on in the last section, safety should always be a priority during periods of fasting, and speaking to a healthcare provider is essential to avoid potential health detriments off the back of your efforts here including –
- Low blood sugar
- Insufficient nutrition
- Negative psychological impact
For individuals who are underweight, pregnant, or diabetic especially, the detrimental impact of fasting can often outweigh any negatives, so it’s vital to seek a professional opinion in these cases.
However, if you’re well-nourished and generally healthy, intermittent fasting is a safe process, especially if you ensure you understand the things you can consume during those periods. Notably, it’s important to remember that fasting does not mean ‘nil by mouth.’ Ongoing hydration is crucial even during fasting periods, if not more so as you aren’t absorbing water from food sources as normal. Note, too, that zero-calorie black coffee and tea are permitted, and can be fantastic as an energy booster if you’re struggling. And, remember – if you’re even in doubt about whether fasting is for you, speak to your healthcare provider to discuss this on a case-by-case basis!
What to Eat When Your Break Your Fast
Many people combine a ketogenic diet with Intermittent Fasting.
There are potential benefits of practicing both.
Fasting and a ketogenic diet both will put you into ketosis and practicing both can speed up the rate that you enter ketosis and ensure you maintain a state of ketosis.
A ketogenic diet when you break your fast will prevent having to fight cravings after your meals.
Start enjoying food again with the help of intermittent fastingThough it may not seem like it, intermittent fasting is an amazing way to start enjoying food again, putting a full stop under restrictive and often ineffective diets, and opening you up to a wider range of health benefits as a result. The main thing is to develop an intermittent fasting schedule that works for you, enabling you to enjoy life, and food, in ways that you possibly haven’t in years.