Last week, I did a nice long run. 13 miles dead on, nice and slow. And before I set out, I had some peanut butter on toast. Not something I would normally do. And, most likely, not something I will do again. I give you the eating-or-not-eating-before-a-run debate. A debate that has rumbled on for decades without much resolution. This is my attempt to resolve it. A bit.
So, whether or not you eat before running has always been a preference thing. Usually I don't (I don't know why I did last week), but many others I know do. For example, my running coach Otto always wolfs down a bar thingy on the train home before a run and says that works for him (the guy ran 5k in 15 minutes and change, and came 11th in the Hastings Half Marathon, so when he talks about running, I like to listen) But what's the CORRECT thing to do in terms of the SCIENCE of fitness and running? Turns out that depends on what flavour human you are; pink or blue.
Dr Michael Mosely has always been something of a cult hero of mine. He loves testing science (usually on himself) and his research has always been practical and solution focused. Anyway, on the most recent episode of Trust Me, I'm a Doctor, he tested athletes who ate breakfast before and after exercise to see if there was any difference in how it affected their bodies. The results were staggering.
It turns out that if you are a man, eating AFTER exercise burns almost 10% more fat than if you eat before. Moreover, this fat burning effect continues for the next 24 hours. Mind-blowing.
Weirdly, however, if you're a woman, eating BEFORE exercise burns loads more fat than if you exercise on an empty stomach; something crazy like 20% more fat burnt.
They did say they weren't sure why this was. Personally, I think it has something to do with the woman's genetic predisposition to retain fat for motherhood. Or something. Whatever the reason, it gives us something to work with. However, whether you eat before or after exercise as a RUNNER depends on what kind of run you're about to do, in my opinion.
The long run, for example. It has two main objectives. Firstly, it makes the liver more efficient at storing glycogen (a type of sugar released from the liver when our blood sugar level drops) and secondly, it makes the body more efficient at using fat as a fuel source. With that in mind, for me, it makes sense to do my long runs on an empty stomach. That said, I do always take a few snacks with me on a long run. Raisins, a banana, a fruit bar thing. But because the objective is related to fat burning, I'd like to do this as efficiently as possible.
However, when it comes to quicker, shorter runs, such as interval training or tempo runs, fat burning is not the primary objective. The goal of these is to maximally stress the aerobic system or lactate threshold, and in these situations, fat is irrelevant; we're running so fast that we're burning sugar, and fat plays much less of a role. So with these ones, I'd grab a light brekkie first to make sure you'll feel okay for the whole session.
So, in summary? If you want to burn fat more effectively, guys-train empty, and girls-train full. However, I think for quick sessions on the track or doing tempos, always have some sugar in you. And seriously, check out this episode:
http://www.bbc.co.uk/programmes/b06vrb6l
It has loads of great stuff on protein shakes (load of pants), antioxidants (double load of pants) and home exercises (try the vacuum lunge next chance you get) and you'll be glad you gave it an hour of your time.
You don't need to eat sugar before you watch it though...
So, whether or not you eat before running has always been a preference thing. Usually I don't (I don't know why I did last week), but many others I know do. For example, my running coach Otto always wolfs down a bar thingy on the train home before a run and says that works for him (the guy ran 5k in 15 minutes and change, and came 11th in the Hastings Half Marathon, so when he talks about running, I like to listen) But what's the CORRECT thing to do in terms of the SCIENCE of fitness and running? Turns out that depends on what flavour human you are; pink or blue.
Dr Michael Mosely has always been something of a cult hero of mine. He loves testing science (usually on himself) and his research has always been practical and solution focused. Anyway, on the most recent episode of Trust Me, I'm a Doctor, he tested athletes who ate breakfast before and after exercise to see if there was any difference in how it affected their bodies. The results were staggering.
It turns out that if you are a man, eating AFTER exercise burns almost 10% more fat than if you eat before. Moreover, this fat burning effect continues for the next 24 hours. Mind-blowing.
Weirdly, however, if you're a woman, eating BEFORE exercise burns loads more fat than if you exercise on an empty stomach; something crazy like 20% more fat burnt.
They did say they weren't sure why this was. Personally, I think it has something to do with the woman's genetic predisposition to retain fat for motherhood. Or something. Whatever the reason, it gives us something to work with. However, whether you eat before or after exercise as a RUNNER depends on what kind of run you're about to do, in my opinion.
The long run, for example. It has two main objectives. Firstly, it makes the liver more efficient at storing glycogen (a type of sugar released from the liver when our blood sugar level drops) and secondly, it makes the body more efficient at using fat as a fuel source. With that in mind, for me, it makes sense to do my long runs on an empty stomach. That said, I do always take a few snacks with me on a long run. Raisins, a banana, a fruit bar thing. But because the objective is related to fat burning, I'd like to do this as efficiently as possible.
However, when it comes to quicker, shorter runs, such as interval training or tempo runs, fat burning is not the primary objective. The goal of these is to maximally stress the aerobic system or lactate threshold, and in these situations, fat is irrelevant; we're running so fast that we're burning sugar, and fat plays much less of a role. So with these ones, I'd grab a light brekkie first to make sure you'll feel okay for the whole session.
So, in summary? If you want to burn fat more effectively, guys-train empty, and girls-train full. However, I think for quick sessions on the track or doing tempos, always have some sugar in you. And seriously, check out this episode:
http://www.bbc.co.uk/programmes/b06vrb6l
It has loads of great stuff on protein shakes (load of pants), antioxidants (double load of pants) and home exercises (try the vacuum lunge next chance you get) and you'll be glad you gave it an hour of your time.
You don't need to eat sugar before you watch it though...
I see the logic but I still don't think I'd run a long run without fuelling first. I get the whole fat-burning thing but I struggle with running performance when running on empty. I need fuel in the tank, especially on a long run. Try a marathon or even a half without fuelling and I'm sure you'd regret it. Very interesting discussion though!
ReplyDeleteOtto
Food for thought
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