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Still got questions about Intermittent Fasting? This should answer all of them.
It sounds crazy – we've been told for so long that skipping meals is bad, and that you need to eat not just to grow, but to also support fat loss.
If that's the case, why then, are so many people seeing success with fasting?
Types of Fasting
There are a number of ways you can employ principles of fasting in your diet.
The first (and seemingly most popular in terms of fitness, fat loss and body composition) is intermittent fasting.
This involves, essentially, reducing the size of your 'feeding window' - the time during the day that you're allowed to actually consume calories. Rather than eat at any time from when you wake up to when you go to sleep, you might fit all of your meals into a 6-8 hour window during the day.
The two most used protocols tend to be Martin Berkhan's 'Lean Gains' method, where you have an 8-hour feeding window, usually having your first meal around lunchtime, and your last at around 8 or 9pm, and 'The Warrior Diet', designed by Ori Hoffmekler, which has just a 4-hour eating window each evening.
The other way you could fast is with more of a daily set up.
'Eat. Stop. Eat' by Brad Pilon embraces this concept by using 24-hour fasting periods once or twice a week.
Some people take this a step further by doing alternate day fasting, and then there are hybrid models.
The 5:2 diet for instance, involves 5 days of unlimited eating, and 2 days with a 500-calorie maximum.
In essence, there are several ways you can fast, but the one thing they all have in common is restricting the times in which you eat, which goes completely against a lot of what those of us in the fitness industry have been brought up on, reading the likes of 'Muscle and Fitness', 'Men's Health' or 'Women's Health.
Busting the Myth
The idea of fasting is in direct opposition to the notion that eating smaller, more frequent meal throughout the day boosts your metabolism.
That's because eating smaller, more frequent meals throughout the day does NOT speed up your metabolism.
Your metabolism doesn't suddenly drop from a few hours of not eating, and calorie intake actually influences metabolism far more than meal frequency.
A 500-calorie meal for instance will burn twice as many calories through metabolism and digestion than a 250-calorie meal, so eating one lot of 500 calories has no different impact on your calorie burn than eating two 250-calorie meals.
In fact, studies tend to show no drop off in metabolic rates when the same number of calories are eaten in the same time frame but spaced further apart. (1)
Why Fasting Works
There's no magic to why fasting works, but there are several reasons why it increases dieting success for some people.
Without a doubt, the main attraction of intermittent fasting is adherence through appetite surpression. Quite simply, having a smaller feeding window (the time when you're actually allowed to eat) means you're likely to feel fuller by cramming all of your daily calories into a smaller time frame. Then, when you aren't eating, food tends to be out of sight, out of mind.
Essentially, eating more in a smaller time frame is going to contribute to greater short term satisfaction, better satiation and less likely to snack - particularly if you get the more difficult part (the fasting) out of the way early in the day. Put in some hard work in the morning by forgoing any food, and then eat like a king in the afternoon.
It can make you less focused on food, and eating bigger meals helps you feel fuller. Every time you eat, your body produces ghrelin - the hunger hormone. The more frequently you eat, the more frequently your body is telling you that you're hungry. With intermittent fasting, however, it's almost impossible to avoid bigger, more satisfying meals, which means you'll eat fewer of them and reduce less ghrelin; this could be a serious positive during a fat loss phase.
Employing daily-style fasts also gives you more licence to go to town a little on the days you do eat.
While sticking to, say 500-1,000 calories on a couple of days a week will be tough, it might be worth it if that means on the 5 days you do eat, you get to eat an extra 300 to 500 over what you would were you to eat the same number every day.
The most important thing to take away from the idea of fasting is that the process of fasting itself is now what allows those that follow it to lose fat - it's the impact it can have on overall energy balance. Fasting itself doesn't burn fat - it doesn't override the laws of thermodynamics. If you want to lose fat, you need to burn more calories than you burn; fasting might just help you with adhering to your diet.
Where Fasting Fails
As with any dietary practice that's a little extreme, fasting can promote a bit of a disordered relationship with dieting.
Restricting food on purpose, even for just a few hours can also have the opposite effect and even lead to cravings or potential binges.
Training can suffer too, particularly if you're a strength athlete and have to train in the mornings. If you're concerned about maintaining strength and performance, it probably isn't the greatest idea to go into a workout having not eaten for 8 to 12 hours, then not eat again for another 3 or 4.
In the same vein, it's important to consider muscle protein synthesis too.
To be kept at optimal levels for anabolism (building and maintaining muscle), you want to spike muscle protein synthesis by consuming protein every 4 to 5 hours. Clearly you won't be able to achieve this overnight while sleeping, but as much as possible, it's a good idea to stick to that maximum 5-hour gap between protein feedings, which fasting doesn't allow you to do.
If it helps you to adhere to your diet better, and stick to the plan more so than splitting your meals up evenly would, then clearly, it's a sensible choice to make, as consistency rules the day.
That said, it might be wise to make just a few tweaks.
Given that fasting itself doesn't actually promote fat loss, a better idea would be to kickstart your day with a small serving of protein to spike muscle protein synthesis, followed by another one a few hours later. That way, you're getting a steady stream of amino acids to the muscles, and still saving the majority of your calories, carbs and fats for later in the day during your so-called feeding window.
Another option is to simply go low-calorie during the day, or stick to mainly protein-based foods, and save your carbs and fats for later in the day, or around your workouts.
For instance, for someone eating 200 grams of protein, 250 grams of carbs and 60 grams of fat per day, their modified 'fast' could look something like –
Remember – fasting isn't a secret trick, or stubborn fat loss solution – it's just a different method of dieting that might suit your personal preferences better than eating every few hours.
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