The Benefits of Intermittent Fasting
Do you want to lose fat, improve your metabolism and experience a whole range of health benefits without having to deprive yourself and give up your favourite foods? Intermittent Fasting might be the answer.
Let’s be clear, Intermittent Fasting is not just for weight loss. Intermittent Fasting is a way of attuning your body to a new metabolism, a new way of processing food, and a new way to give your body the time and energy it needs for other beneficial internal functioning to take place. For most people’s day-to-day diets and eating schedules, our bodies are constantly digesting foods. We finish a meal, and we might snack a couple of hours later, followed by another meal later on, in a perpetual digesting cycle. Whatever the foods consumed may be, or portion size, our bodies are constantly having to focus on digestion. However, by fasting intermittently, we allow our bodies time and space to focus on other internal processes and encourage our bodies to alter our metabolic rate.
Firstly, we can address why Intermittent Fasting might work for you over and above usual diets. Intermittent Fasting is often easier for people to stick to. Rather than consistently reducing your calorie intake day after day with foods that don’t excite you, which is easy to undermine with impulsive binges, Intermittent Fasting allows you to still eat all the foods you enjoy. Instead of enduring a “diet” that deprives you of certain foods, fasting periodically creates an eating pattern controlled by timing instead. It controls when you eat and drink, as opposed to what you eat and drink. To this end, with Intermittent Fasting, you are forced to eat more intentionally, planning what you can enjoy eating in your allotted time-frame, rather than eating mindlessly as and when you feel hungry.
How does Intermittent Fasting work? After we eat, our bodies use carbohydrates (e.g. glucose) from our food for fuel. If there is extra fuel left over, then our bodies store it as fat for future use. With fasting, just as during extended exercise, our bodies flip from using glucose (and storing fat), to using that stored fat and ketones (made from fats) for fuel. This is sometimes called the “G-to-K switch,” which represents our bodies switching from glucose-to-ketone and therefore subverting what our bodies would normally use as fuel. Here we see our “metabolic flexibility” in action. Depending on the person, this “flipping" of the metabolic switch (that takes place when our stored glucose levels are depleted) can occur anywhere from 12 - 36 hours after our last meal. It is at this point that our bodies begin to release the fats in our cells into our blood, metabolising them into ketones which go on to fuel our cells with “high metabolic activity.” Here, we are burning fat, while using ketones to fuel our muscles, rather than continuously storing fat. This Intermittent Fasting also then helps our brains - our learning, memory, and mood - because our neurons start using ketones for fuel, and so our brain functioning and brain-derived neurotrophic factor (BDNF) increases. As a result, BDNF helps enhance synaptic plasticity (changes in our brain that help with learning and memory), which also allows our neurons to better resist stress.
To help explain this, we can look back to more historic times when we, and many animals, were evolving. As “hunter-gatherers”, us humans would have to survive short periods of fasting in between finding food to eat. Eating would be sporadic and unpredictable - sometimes it might be nut and berries, other days it might be meat and protein. Back then, if we had to act quickly to secure our dinner, our bodies would still have the energy reserve to survive and think quickly, even if our last meal was hours before. Our bodies had developed in such a way that we could survive hours after our last meal and still function with maximum impact, burning stored fats as and when we needed to.
We now know what happens physically within us, but how do we put this Intermittent Fasting into practice in reality? How can you fast intermittently to maximum effect? There are lots of ways, whether daily, weekly or monthly, all of which work on a person-by-person basis:
Alternate-day fasting (ADF): This involves one day of fasting and then one day of “feasting” which you can continue on alternate days.
Alternate-day modified fasting (ADMF): With this you can eat 25-40% of your daily needs one day, and then eat normally the next which you continue on alternate days.
Periodic fasting (PF) or “Two day” fasting: Each week you have 1 or 2 days to eat very few calories per day (e.g. 0-880 calories per day). And then the other 5 days you eat normally. For example, the 5:2 diet, where you eat no more than 500 calories per day for two non-consecutive days each week.
Time-restricted fasting (TRF): With this you should fast for 12-16 hours every day (which includes sleep) and eat normally during the other 8-12 hours.
One 24-hour period of fasting each month.
With each of these methods, you are able to give your digestive system a proper break in a way that is sustainable. However, it is very important to keep in mind that reducing your food intake also risks reducing your nutrient intake. It is therefore vital to ensure that even when fasting you get enough essential nutrients for your long-term health.
Why is Intermittent Fasting important for us? Historically, studies have shown that people who reported routine fasting (whether for religious reasons or not) had a lower risk of heart disease, lower blood sugar levels, BMIs and risk of diabetes. Add to these, lower blood lipids, better blood sugar management, improved insulin sensitivity and lower levels of inflammation, Intermittent Fasting, and the weight loss it contributes towards, helps improves a healthy lifespan, as well as improving the functioning of both body and mind. The idea of Intermittent Fasting is now gaining a lot of traction, as an emerging area of research with results that are looking very promising. Studies have shown that Intermittent Fasting makes our metabolism far more flexible, allowing us to preferentially burn fat while preserving our muscles. On the flip side, according to Michelle Harvie and Anthony Howell, “Metabolic inflexibility is thought to be the root cause of insulin resistance.” Other researchers have also discovered that, “When taken together with animal studies, the medical experience with fasting, glucose regulation and diabetes strongly suggests IF [Intermittent Fasting] can be effective in preventing type 2 diabetes.” Intermittent Fasting is not a quick weight loss fix - it’s a new way of structuring your diet that promotes long-term health benefits.
On top of this, as well as physical health benefits, as we have explored, Intermittent Fasting has benefits to our brain functioning and mental health. Many animal studies have demonstrated ways in which intermittent fasting can help improve cognition and our ability to think. For example, when mice fasted on alternate days for 6-8 months, a study showed that they performed better in several learning and memory tests, compared to mice that were fed daily. Studies also show that alternate day fasting protects brain neurons in animal models of Alzheimer’s, Parkinson’s, and strokes, and reduces oxidative stress in the brain. Research into this area of Intermittent Fasting is still relatively new; however, longer term human studies of different calorie reduction diets, including Interment Fasting, will hopefully shed further light on the effects on cognitive performance and mental health.
If you are considering trying Intermittent Fasting, then it is important to check in with your body, mental health, and if necessary a healthcare provider, to ensure this change in diet is right for you. A number of adverse effects have been reported from Intermittent Fasting that shouldn’t be ignored. Without raising too much alarm, as this won’t be the case for everybody, some people may experience bad temper, low mood, lack of concentration, feeling cold, nausea, vomiting, constipation, swelling, hair loss, muscle weakness, uric acid in the blood and reduced kidney function, menstrual irregularities, abnormal liver function tests, headaches, fainting, weakness, dehydration, mild metabolic acidosis, preoccupation with food, erratic eating patterns, binging, and hunger pangs. Moreover, if done too often or for too many days, Intermittent Fasting can have more serious effects. Even in healthy adults, if done for several weeks (about 5-7 weeks) fasting becomes starvation, and at this point your body starts consuming muscles and vital organs.
Ultimately, however, Intermittent fasting is all about being mindful and listening to your body. It might not work for everybody, but for those who can adjust their eating schedule sensibly and see real benefits, it really is a way to becoming more mindful about what and when you eat. As discussed, Intermittent fasting is a way of enjoying the benefits of regular calorie reduced diets without restricting what you eat, and instead just when you eat it. Not only does it help reduce excess fat and weight, it has other benefits on both the body and the brain as a result of increasing our metabolic flexibility. As ever, more research is definitely needed to really understand the long-term benefits of Intermittent Fasting on the body and brain, as well as which approach is optimal for different people and different health goals, but under careful, and considered, conditions it is a great choice for many of us.
For more advice and tips on how to make Intermittent Fasting work for you, please do get in touch with Aliya Jasrai at Hayya Health.
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