Eating for Exercise

Carbs

It’s 6am and the alarm’s going off for your morning sweat-session. You drag yourself out of bed, pull on your training gear, down a cuppa and head out the door. You’re ready for a productive workout, right? Wrong!

There’s something missing from this morning routine: FUEL.

Why?

Sure enough, you could follow this routine and have what feels like a perfectly good training session, but evidence suggests that exercising on an empty stomach actually results in reduced endurance, exercise intensity, and possibly even reduced fat burn1,2,3.

In fact, if you’re trying to lose weight, exercising without prior fuelling can even cause you to eat more throughout the day than if you’d had a carbohydrate snack3,4.

The reason for this is a dip in blood sugar levels, causing fatigue, light-headedness, weakness, shakes etc. which could cut short your workout or put you at risk of injury. Even if you manage to finish your workout, chances are you won’t have been able to put in as much effort, therefore burning fewer calories overall.

A snack or light meal, eaten 2-4 hours before exercise, slows the speed at which glycogen is used up, resulting in a longer, harder workout3. This applies to morning, noon or night exercisers.

What?

As we already know from “Running on Empty”, foods rich in carbohydrate are the main source of fuel for our bodies, but more specifically slow-release carbs are the best foods to consume before training. Slow-release carbs (otherwise known as “low GI” or glycaemic index) are foods that cause a gradual rise in blood sugar levels, rather than the spike we see from high GI foods. However, high GI foods can be made “slow-release” by combining them with protein or fat (more on this in another post!).

Low GI snacks or meals include:

  • porridge with milk
  • wholegrain cereal and milk (try bran flakes, muesli or Weetabix for healthier cereals)
  • cereal bar or breakfast bar (Nature Valley or Eat Natural are good choices)
  • 1-2 pieces of fruit (apples, bananas, grapes)
  • handful raisins or other dried fruit
  • a smoothie
  • natural or Greek yoghurt
  • a glass of fruit juice diluted with half quantity water
  • a glass of milk
  • peanut butter on toast (or a bagel)
  • sandwich filled with chicken, tuna, egg
  • small jacket potato with baked beans, tuna, chilli
  • rice with chicken or fish and veg
  • pasta salad or pasta with tomato sauce and vegetables
A personal favourite pre-workout snack: peanut butter on toast

How much?

This depends on how long you plan to exercise for, what intensity you will be working at, and also how much you weigh.

In general, sticking to around 1g of carbohydrate per kilogram of body weight should be enough for up to two hours’ moderate intensity exercise (this equates to around 64g of carbohydrate for a 10 stone person). For longer workouts or events, try 2g per kilo of body weight (128g of carbohydrate for a 10 stone person).

Remember, 100g of pasta does not provide 100g of carbohydrate – it’s actually only around 70g. The carbohydrate content of all foods should be listed on the packaging, so take care to make sure you are consuming enough for your needs.

Eating for Exercise

Check food labels for carbohydrate content

When?

As already mentioned, eating something carbohydrate rich around 2-4 hours before exercise should provide enough energy to keep you going, but you don’t necessarily need to take on extra calories in order to do this. If you are watching your weight you can time your ordinary meals/snacks to tie in with your training.

For example, for those morning exercisers, why not split your breakfast into two portions? One part for before your session, and one to re-fuel after? Or if you really can’t face solid food first thing in the morning, try a glass of juice mixed with water, or a smoothie or glass of milk.

If you exercise at lunchtime, your breakfast may be enough to fuel you, but if not, you could have a piece of fruit or a cereal bar mid-morning to give you a boost.

If you like to train after work, a larger lunch or a mid-afternoon snack will keep you energised. And for late evening exercisers, try a smaller dinner so as not to fill you too much, with a snack for afterwards.

What about events?

For events and races, don’t leave it to chance. You should always stick with what you know and follow how you’ve eaten during training. Don’t try any new foods in the build up to the event, or on the day, and don’t rely on there being what you need en route or at the venue – take your own supplies!

Fuelling doesn’t have to be a chore, it just takes a little bit of planning.

Next time on Sports Nutrition: food for recovery.

Further Reading:

  1. Kirwan, J.P., O’Gorman, D., Evans, W.J., 1997. A moderate glycemic meal before endurance exercise can enhance performance, Journal of Applied Physiology, [online] Available at: http://jap.physiology.org/content/84/1/53.abstract [Accessed 16th October 2012].
  2. Schoenfeld, B., 2011. Does cardio after an overnight fast maximize fat loss?, Strength and Conditioning Journal, [online] Available at: http://pulsthjalfun.is/wp-content/uploads/2011/11/doescardio.pdf [Accessed 16th October 2012].
  3. Bean, A., 2007. Food for Fitness. London, A&C Black Publishers Ltd. Pages 37-44.
  4. Melby, C.L., Osterberg, K.L., Resch, A., Davy, B., Johnson, S., Davy, K., 2002. Effect of carbohydrate ingestion during exercise on post-exercise substrate oxidation and energy intake, International Journal of Sports Nutrition and Exercise Metabolism, [online] Available at: http://www.ncbi.nlm.nih.gov/pubmed/12432174 [Accessed 16th October 2012].