At first glance, intermittent fasting seems pretty counterintuitive when it comes to improving body composition. The idea of skipping breakfast, consuming zero calories for several hours on end and then feasting within a designated time period goes against much of what’s typically believed to be optimal for fat loss and muscle retention.
However, the truth is when done properly, intermittent fasting can be a great tool to help you lose fat faster and for good, all without sacrificing tons of muscle mass in the process.
Before we get into that it’s important that you first understand that intermittent fasting is by no means anything magical. The largest systematic review covering 40 studies on the topic found that when calories are equated, although intermittent fasting may provide various physiological and psychological health benefits, it does not provide any direct benefit for increased fat loss or muscle gain when compared to traditional dieting.
Simply meaning, that at the end of the day the calorie deficit is what ultimately produces fat loss when fasting rather than the act of fasting itself. However, the great thing about fasting is that it makes sticking to your calorie deficit much easier. Not only does research showed that it suppresses your appetite better than traditional dieting but by ingesting all of your calories within a shorter time period you’re able to incorporate larger & more satisfying meals – that help you stay full despite being any calorie deficit. Therefore it’s likely to lead to better adherence and more fat loss for you in the long run.
How to fast?
If your main goal is to draw body fat while minimizing muscle loss, stick to the 16-8 protocol popularized by Martin Birkin. This simply involves fasting for 16 hours and then eating within an 8-hour feeding window. For example, only eating between 12 to 8 p.m. and fasting outside of these hours. It’s as simple as skipping breakfast but if you struggle with this you can gradually build up to 16 hours of fasting overtime and gradually increase the number of days you fast per week.
The time of day of your fasting and feeding windows are of little significance. The key though is to be consistent with when they take place because it enables your body to adapt by suppressing your hunger hormone during the time of your fast. It does often take around 2 to 3 weeks for your body to adapt but it will become much easier over time. It’s also worth noting that females may have slightly more adverse reactions to fasting than men. It means that it’s a good idea for females to start with a 14-10 protocol and then build up to the 16-8 over time.
What to eat during fasting?
During the fasting period, you don’t ingest any calories or anything that spikes your insulin. It is however suggested to drink a lot of water as well as black coffee/green tea or sparkling water while staying busy in order to help suppress your appetite. Most calorie-free sweeteners don’t have an appreciable effect on insulin and are therefore fine to have during your fasting period.
For your feeding window, the actual foods you should be eating are no different than the foods you should be eating with any fat loss diet. Aa good rule of thumb is to stick to 80% of your foods coming from whole unprocessed sources.
How much to eat in your feeding window?
There’s no strong evidence that intermittent fasting will help you lose fat without also being in a calorie deficit. In order to calculate the amount of calorie intake, multiply your body weight and pounds by 13. This will provide you with roughly the amount of calories you need to ingest daily in order to begin a calorie deficit such that you’re able to lose around a pound a week.
Your protein intake will also be vital to maintaining your muscle mass as you lean down so a minimum intake of roughly 0.173 -1gm of protein/lb of body weight would be ideal. For example, a 170-pound individual utilizing intermittent fasting should place a priority on hitting these two main goals during their feeding window:
- Calories intake ~ 2200 Calories
- Protein intake ~ 124-170g/lb
As for the optimal number of meals to eat during your feeding window, the best and most convenient option is to stick with three protein-rich meals. This not only enables you to have larger or more satisfying meals as you’re dieting but as shown in this paper that compared ingesting three large meals versus six smaller meals throughout the day three meals seems to be the better option for hunger control.
Although this will likely vary individually in addition contrary to popular belief as shown in this paper from the Journal of nutrition. When compared to eating more frequently, a lower meal frequency doesn’t cause a reduction in your metabolism. It’s your total calorie content and composition of your meals that governs this rather than the actual frequency at which you eat.
However, that research indicates that there may be a slight advantage to spacing out protein over for meals rather than three in terms of maximizing protein synthesis. Meaning, that if your main goal is instead to build muscle, fasting may actually be suboptimal. For this reason, it is likely of little significance if you’re still consuming adequate protein with your three meals which are the more crucial factor. Regardless though, experiment with it and stick to a meal frequency that best suits your lifestyle.
When to train during fasting?
There are various potential benefits to fasted training and various benefits to training in a fed state. Tthe best option for you will ultimately depend on your schedule and also what enables you to perform the best in your workout. But in either case, there are a few things keep in mind in the event that you have to wait trained fasted in the morning.
During intermittent fasting, the timing of your post-workout meal becomes of greater importance in order to minimize any potential muscle breakdown. It means that you should time your first meal such that you’re able to ingest it shortly after your workout and it should ideally be rich in protein and carbs. But if you’re unable to do this based on your schedule and feeding window a good alternative is to simply ingest essential amino acids during your workout or a whey protein shake afterwards.
Although, this will technically spike your insulin and break your fast but you will still get the benefit of pushing your calories later on in the day which is ultimately what makes fasting such a powerful tool for fat loss. Whereas in the event that you train within your feeding window for example after work you’d want to time as such that you’re able to get in a meal or two with adequate protein and carbs before your workout and have a meal sometime post-workout.
The timing now is not as important as it was with fasted training but again experiment with it and see what works best for you and what you’ll be most consistent with.
Fasting is nothing magical in terms of fat loss but for many, it does make easier for you to stick into a calorie deficit that which is why it can be such a powerful tool for fat loss especially when you pair it with the right training plan.