FAT OR CARBS TO FUEL TRAINING?
Is it a good idea to adapt my diet to burn fat as fuel? Is this more efficient than using mostly carbohydrate to fuel my training? I’ve read a lot around this subject recently but am still unsure what the best approach is.
NOEL CHANDLER, EMAIL
There’s a real misconception that the only way to burn fat for fuel is to remove carbohydrate from your diet. But we know that our body actually uses a mix of both fat and carbohydrate for fuel, relying more on fat stored in the muscle in low-to-moderate intensity training.
We also know from numerous studies over the past 20 years that as exercise intensity increases, that is, above 65% of you maximum HR, the body needs carbohydrate in order to be able to maintain these faster paces. This doesn’t mean we stop using fat for fuel, but the body will rely on carbohydrate, which can be broken down into glucose and delivered to the working muscles quickly and efficiently.
In actual fact, it’s endurance training and SOME diet manipulation that actually improves ability to oxidise fat for fuel, NOT just removing carbohydrate from your diet.
My general advice is to do low to moderate training sessions in a fasted state, for example first thing in the morning, to make your body more efficient at using fat as fuel. You can also try avoiding carbs in the four hours before training.
Prior to higher-intensity sessions, including carbohydrate before and after is key in order to ensure you can hit the paces needed for progression. The ‘fat adaptation’ from doing your fasted sessions will still be of benefit as, even at these faster paces, you will burn a higher percentage of fat as fuel alongside carbohydrate, meaning you can spare your glycogen stores for longer.
If you never train with carbohydrate, the problems you’ll encounter is that firstly, you won’t be able to hit high-intensity paces and secondly, your body will not be able to absorb carbohydrate as fuel during high-intensity exercise as it will not be use to it, which will be detrimental to performance on race day.