Intermittent fasting (IF) has gained some serious notoriety over the years. Whether it’s 16/8 or 5:2, IF supporters claim intermittent fasting is responsible for incredible fat loss, muscle growth, increased brain function, and better recovery, while eating whatever you want during your feeding windows.
But this isn’t exactly true.
IF is promoted as some magical diet, when it’s literally just a way of eating food. You have a period where you don’t eat (fasting) and then a period when you do. We all do this when we sleep, hence why our first meal is called breakfast – you are breaking the fast. It’s just that some people decide to eat breakfast (or break their fast) later in the day.
There’s two major schools of thought around breakfast. One is that breakfast is the most important meal of the day and you should eat as soon as you can upon waking or your body will go into starvation mode and start eating away at your muscles. The other is that you should fast for a minimum of 16 hours per day in order to maximise brain function, increase growth hormone, and basically become jacked and shredded beyond your wildest dreams.
The reason IF appears to work better for fat loss is that it’s easier for people to control their calorie intake if they have fewer hours during which they’re eating. If they’re in a significant calorie deficit, having a smaller feeding window will generally enable them to eat bigger meals as they might only eat one or two meals as opposed to 3 meals plus several snacks throughout the day,
The claims about muscle growth and improved brain function are not well substantiated. The research on IF is limited at best and there’s even less research done on the impact on women. However, the general consensus is that long periods of fasting for women can be detrimental to their hormonal health and can cause or reinforce disordered eating patterns. This is a major concern and is the reason why we never recommend long fasts for our female clients.
The IF crowd also claims that training in a fasted state optimises fat loss and muscle growth. There might be marginally more fat oxidation training in a fasted state versus a fed state. However, this isn’t worth worrying about if you have less energy in a fasted state and your training output decreases as a result. Therefore, you’d be better off eating before you train and improve your training outcome.
However, as with everything, different things work for different people.
You might be ready for a meal as soon as you wake up or you might not feel hungry until a few hours later. Both are ok.
If you train early in the morning and feel like you need to eat beforehand to get the most out of your training, then do that.
If you can train just fine on an empty stomach, that’s fine too. Just remember, you’ll assist your recovery and muscle growth if you have protein and carbs reasonably soon after training.
We also recommend having regular protein feedings throughout the day, which is beneficial for a) muscle protein synthesis and b) ensuring you eat adequate protein. As protein increases satiety (keeps you feeling fuller for longer), if you’re doing IF and eat a meal with a large amount of protein, you may not be in the mood to shove in more protein before your feeding window closes; however, if you space out your protein intake throughout the day, you can easily hit your protein requirements.
Pay attention to your hunger signals and your energy levels before and after eating and see what works best for you. You might even find that you have different needs on different days, which is also normal because you aren’t a robot.