Is intermittent fasting really the miracle solution to losing fat, gaining muscle and living healthily?
Is it the all-rounder diet which could help to reach all your goals - muscle gain and fat loss - at the same time (even if they contradict each other)?
What if I told you that IF can actually make you lose muscle and gain fat if you don’t do it right?
What to learn how to do it right? - Then read on.
IF 101
Fasting should usually be done overnight and extended into the morning, whereby the first meal is lunch. Usually a person’s last meal would be in the evening, ie dinner, then they start IF again which continues through the night until the next day again, where their first meal is lunch.
It is important to highlight that there is no strict rule to this. In theory, you could also have breakfast and lunch, skip dinner and fast overnight.
How you arrange your fasting window and its length is dependent on your schedule and your personal preference. There is no fixed time or window for IF itself and when you should eat. Some people will have a 4 hour window, some may have 6 and some will have 8 hours. Again, this entirely depends on YOU.
What is important is structuring your meals. You shouldn’t just eat anything at any given time during your non-fasting-window. There are many benefits to a structured meal pattern, including the most obvious of not just randomly eating and thereby running into the danger of overeating.
So why do people IF and why is it beneficial?
I often get the impression that many people do IF because they think that it is another miracle solution for fat loss and possibly lean gains. Another diet that offsets fundamental energy balance principles (ie you need to eat less than you expend to lose weight) and makes you lose more fat than other diets do.
IF is definitely more beneficial for people, that want to lose weight as opposed to those that want to gain weight or muscle. As a result of the shorter eating-allowance-window, it is more difficult to get more calories in, therefore this would be difficult if you were say a big guy that needs to get 5000 kcal in/a day!
If you were a big overweight guy that wants to lose weight, not being able to get 5000 kcal in is a good thing. On the other hand, if you were a ripped active dude who needs 5000 kcal to make muscle gains, not getting these in because of the limited eating time is not a wise strategy for your goals.
As always, it is important to use common sense for the entire issue. A shorter eating window does not guarantee that you won’t overeat in this period and lose weight automatically. Everything depends on your food choices. If you eat high-calorie junk in your short feeding window instead of calorie-reduced meals that bring you into an energy deficit, then you actually can gain weight with IF. It doesn’t matter what strategy you use, the general principle for weight loss stays the same: you need to expend more energy than you eat.
Speaking of energy expenditure, there are equally some negative things about IF too.
Fasting periods of 20 hours or longer (if your eating window is 4 hours or less) causes your basal metabolic rate (BMR) to decrease; thus, your metabolism slows down even at times when you don’t fast (ref). BMR is the energy you spend for your basic tasks, such as for your heart to beat. I personally would not recommend to anyone to fast more than 18 hours anyway.
Fasting causes you to move less during the fasting period, thereby causing you to expend less energy overall (to learn more on this topic, join the Bayesian PT Course). IF isn’t ideal for people that are very active in the mornings, it probably has a smaller negative effect on those that are more sedentary (ie office based jobs). If you have a very sedentary occupation, e.g. sitting in front of your computer all day, then it probably won’t matter too much for your total daily energy expenditure (TDEE), other than that you may become lazier and start writing shorter emails! However, if typing emails is the task you expend the most energy on during the day, then perhaps you need to look into other things you could do ensure you are moving more.
However, if you are active during the fasting times (e.g. you are doing lots of housework), fasting may decrease your TDEE, thus you may lose less weight at the end, compared to a diet with the same calorie intake, but without intermittent fasting.
In general, if fasting saves you enough calories to overcome the 'moving less and expending less' trade off and you like the strategy, then you can use it for weight loss. That is subject to having the time restriction being helpful for you. If not, then it's not a good strategy for you.
Here is an example:
A busy house wife usually prepares food in the morning and may snack unnecessarily on food while preparing it. The unnecessary snacking adds 250 kcal to her calorie intake every day. By starting IF and putting a restriction on not eating in the morning, she starts consuming 250 kcal less a day. However, because she fasts she starts moving less and expends 100 kcal less in the morning - in total, she has saved 150 kcal (250 kcal from not snacking - 100 kcal from moving less) compared to before. For her IF makes sense.
However, if her energy expenditure goes down by 300 kcal as a result of her decreased movement in the morning, fasting wouldn't make sense. The energy she did not burn is 50 kcal higher than the energy she saved by not snacking.
Another situation in which IF can be disadvantageous is when IF triggers overeating. The restricting of eating times is mentally difficult to handle for some people, especially those with a history of eating disorders or chronic dieting. This can result in the loss of control and overeating in the feeding window, which is not only bad for weight loss, but can also result in the development of disordered eating behaviour and other psychological problems, like the feeling of guilt or being unhappy with oneself.
IF and muscle gain
As already mentioned before, IF is probably not the best method for muscle gain for most people, especially for beginners to resistance training.
If you are a beginner, your anabolic window is really long, so after training you can build muscle for up to 72 hours. If you start fasting within those 72 hours, then you will not support your body with enough energy to build muscle.
However, the more advanced you get then the shorter your anabolic window gets. Therefore, if you are an advanced lifter whose anabolic window is say 16-24 hours, IF wouldn’t be such a big problem if you goal is body recomposition, ie simultaneous fat loss and muscle gain. In this instance what you can do is make sure your bigger meals are after your workout, some food before your workout, and fast before that time to lose fat. In general, training in the fasting window is not the best thing to do.
Nevertheless, if you are an advanced lifter and you want to focus on building muscle, then it doesn’t make sense to keep fasting windows longer than necessary (e.g. in the case of overnight fast), as during the fasted state the body breaks down more muscle to fuel its energy needs than in the fed state. If you really want to make big gains, then your goal is not only to maximize your muscle protein synthesis, but also to reduce the breakdown as much as possible, as it is the difference between the both that matter in the end for overall muscle gains.
In the second part of this article, I will talk about my personal experience and findings when utilising IF as a dieting protocol. Stay tuned for part two next week!
PS: If you want to make sure you are following the most optimum nutritional plan for your current goals and learn the tools to make your diet work for your lifestyle and not the other way around, then check out my Customized Macros Package!