Lots of the stuff in our body is fuel for living. This includes fat. It’s harder to get energy out of fat than it is to get energy out of muscle glycogen. However muscle/liver glycogen is limited and in endurance events it may well run out. Then you stop. Literally stop.
So you take on board energy when you train and race but sometimes that too is not enough to perform optimally.
It is possible to train your body to better burn fat. This is great as it, simplistically, makes you thinner but it also puts further away that point where you run out of glycogen.
This probably won’t help your 5k much but the further over 1 hour your event goes the more important it becomes.
So how do you do it?
1. Eat a high fat meal BEFORE exercise. However this is only for long exercise periods of at least 90 minutes. The abundance of fat is recognised by your body and your body tries to use it more than it otherwise would. This strategy is for serious athletes only!
2. For shorter workouts eat nothing beforehand. ie make sure it was at least 2 hours since your last Low GI meal. Only use water during the exercise.
3. A longer term dietary strategy is to eat a low GL based diet. Again this makes the body metabolism shift towards using fat as a fuel source.
4. Do moderate (sweating) exercise for extended periods. If you do too much speedwork then the energy required for the speedwork is too great and that can ONLY be quickly got from muscle/liver glycogen. So the longer/moderate stuff lets your body practice drip feeding itself, partly, from your fat stores.
5. Do muscle building exercise (not body building!! but you can if you want to) ie fast running. Bigger, stronger more efficient muscles burn more energy whilst at rest. They do not necessarily burn the energy within the muscles themselves they also burn fat.
Remember one big problem with diets and exercise is that people do not re-fuel themselves properly.
- What’s the point of doing a massive 3 hour run and then not re-fuelling properly. If you don’t take on board enough carbs water and protein then the muscles will not repair themselves and will not ‘fill up’ with energy.
- What’s the point of going on a diet and cutting out protein so that your muscles waste away? As soon as you start eating again the extra energy is stored straight away as fat!!
- What’s the point of not drinking enough water, other than being bad for you, as soon as you drink water again you put that ‘weight’ back on!
So, some of the above points appear contradictory. Which is kind of true.
However what it is really telling you is that you need a balanced exercise regime AND a balanced dietary regime. You need to do long runs AND fast runs. You need to eat protein, carbs and fat (and water, not too much fat please!). 5k training is a great way to balance the exercise and, for the sake of argument, a low GL diet (look at the food packaging’s labels, it’s on there) is a good enough one for the food. To lose weight quickly try the Atkins diet but the lack of carbs in it will cause you problems with life and exercise soon enough!