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Fasting is all the rage in the health and fitness world… But with so many conflicting opinions and versions of fasting out there, what is the most effective and realistic way to introduce fasting into your lifestyle to receive optimal benefits?
At its core, fasting simply means alternating between periods of fasting and eating. This can come in many different forms, with some of the most common being:
18:6, where you fast for 18 hours (including overnight) and limit food intake to 8 hours of each day
5:2, where you “fast” or consume very few calories (500-600) for two days each week, and eat normally on the remaining five days
24-hour fasts, done 1-2 times per week, or even less frequently, during which you eat little to no food.
Instead of restricting foods or food groups, fasting restricts your eating window in the aim of reducing your calorie intake across a day, or a week. So for many people, it’s less prescriptive than a diet, and more of an eating pattern or lifestyle choice.
Interestingly, the concept of fasting dates all the way back to our ancestors. Ancient hunter gatherers often were unable to find or hunt food, meaning they evolved to be able to function and survive without food for long periods of time. So in this way, occasional fasting is more in line with our biological makeup than our normal 3 or 4 meals per day.
So the emphasis in recent times on fasting originates from this idea. Over time, more money and research has been poured into the phenomenon, making it more mainstream and popular as a weight-loss tool or diet alternative.
The short answer: by reducing calories, you’re likely to lose weight. The fact is, intermittent fasting is simply a diet in disguise, designed to reduce the amount of food you eat in a day (or week). So while it may lead to short-term weight loss for this reason, there’s no “magical reason” fasting is effective for weight loss.
In fact, in the long-term, it’s likely to slow your metabolism as the result of decreased food intake. So while it may assist with weight loss in the short-term, or when done sporadically, it’s unlikely to lead to long-term, sustainable weight or fat loss.
Similarly, there’s some evidence to suggest fasting can also cause you to lose muscle mass. As we know, the more muscle we gain, the more our metabolism speeds up, so this isn’t a positive result for those looking to lose fat.
We’re always hearing about all the other non-weight related health benefits of fasting, but do these stack up?
Fasting can create changes within your body’s natural processes and cells, which can be both positive and negative.
Hormonal Changes
Fasting can interfere with your body’s natural hormone production, by sending a message to your brain that your body is starving during prolonged periods of starvation. As a result, the production of your stress hormone (cortisol) may increase, leading your body to store more fat to use as food when it’s hungry.
This can also cause changes to the production of sex hormones, leading to imbalances in your body, potential weight gain, and even interruptions to the female menstrual cycle.
Women, in particular, should be wary of fasting for more than 14 hours at a time, as this may lead to negative impacts on your hormones.
Insulin Sensitivity
There is some evidence showing that fasting can improve your insulin sensitivity, or your body’s ability to use the glucose in your blood more efficiently as fuel. In turn, this can improve your energy levels and reduce your risk of diseases such as type 2 diabetes and insulin resistance.
However, exercise is another way to improve your insulin sensitivity if you’re not sold on the idea of fasting. Arguably safer and with a whole host of health benefits including improved mental health and clarity, exercise is an excellent addition to your daily routine if you’re looking for the same benefits!
Your Metabolism gets a Break
So many people claim that one of the key benefits of fasting is its ability to give your metabolism and digestive system a “break”. But guess what… They don’t actually need a break! While it’s ideal to have at least a 12-hour window between dinner and the next morning’s breakfast (during which time you’ll mostly be asleep!), your body’s processes don’t actually require any longer than this to function at their best. So this benefit is essentially redundant and unnecessary.
Or should we say, the lack of evidence… Interestingly, most research around fasting is in its very early stages, with almost all existing studies being performed on animals like mice. As a result, a lot of the claims you see out there are just that: claims! They’re essentially marketing a diet alternative to you, based on evidence that doesn’t exist.
All research we have at the moment is inconclusive, and shouldn’t be heavily relied upon.
Fasting is absolutely not recommended for anyone who struggles with disordered eating or behaviours, or has suffered in the past. It can be very triggering for many people, so proceed with caution.
Otherwise, now that you know the evidence (or lack of) behind fasting, you can decide for yourself! In terms of picking the fasting method that’s likely to give you the greatest bang for your buck, most people find the 16:8 intermittent fasting method to be the easiest to follow and the most sustainable. It’s definitely the most popular option if you do decide that fasting is the way to achieve your weight-loss and health goals.
Or, if you’re unconvinced, or feel you don’t need any form of restrictive diet-in-disguise to help you achieve your goals, simply recommit to eating a balanced diet rich in whole foods, and hit the gym regularly to gain all the benefits fasting promises, and more!
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