How intermittent fasting impact bodyfat and performance
/What if you took a group of people and split them into 2 groups:
Group 1: Eat normally (3 meals a day)
Group 2: Eat the SAME number of calories and fat/carb/protein ratio but all within an 8 hour window.
Would you see any impact on body composition, health, athletic performance?
I’m a big fan of “intermittent fasting”, or what is more scientifically referred to as “time restricted eating” (TRE).
This is the concept of eating all of your calories within a narrow window of time (e.g. 8 hours).
There have been countless studies which have demonstrated the positive effects of such an approach to eating.
This is why I was intrigued when I saw this new study, which examined the effect of TRE on health and performance parameters.
They took a group of male cyclists and split them into 2 group, as per above: one group ate “normally”, the second group ate the exact same calories and macros (fat/protein/carbs) but all within an 8 hour window (between 10am and 6pm).
They did this for a period of 4 weeks, kept them training hard, and measured a number of health and performance parameters.
What they noticed was the following:
The TRE group lost bodyweight and fat, but not muscle
Peak power was not affected between the 2 groups
But the TRE group became faster, because they kept producing the same power but at a lower bodyweight (power / weight ratio is very important in cycling and other sports)
Inflammation was significantly lower in the TRE group.
What does this mean?
The main message is that eating within a time restricted window without cutting calories:
Can help you lose fat while preserving muscle;
Can reduce inflammation, which means you recover faster and can train harder.
The study was for 4 weeks. In my experience and based on other studies I’ve read over the years, you don’t want to be doing TRE all the time, especially with hard training.
TRE is a form of stress on the body, and too much stress for a long period of time without a break can start to impact hormonal balances and immune system activity.
So my advice is to cycle in and out: 4 weeks of TRE followed by 1 week of normal eating.
And if you’re female, you want to be more careful: studies have shown that TRE and fasting in general can lead to hormonal disruptions if done too often and too aggressively. So listen to your body!
I have written extensively about fasting in the past, including:
