To eat or not to eat?


A few people over the summer have asked me whether you should eat before a workout – particularly when rushing to make 9.30am boot camp.  If you do an internet search on this subject it throws up conflicting and confusing advice so here is what I have learnt on my many nutrition courses coupled with a dose of common sense!

There are now lots of articles available which advise exercising on an empty stomach as it forces the body to burn fat rather than glucose.

Your body doesn’t like burning fat as an immediate energy source, it likes glucose and then when glucose is not available it will turn to protein (muscle) and then fat.  The process however are a little more complex than that you actually burn a mix of glucose and fat the proportions of which depend on the intensity and duration of your exercise.

You may have heard that low to moderate intensity exercise such as walking burns more fat as fuel than high intensity sessions which rely on available glucose from food.  That is true but overall you have to walk for a long time to burn as many calories as you do in a more intensive session.

When you exercise at a higher intensity the body needs glucose to perform at maximum levels and push that heart rate up. Your active muscles rip through the available glucose and glycogen stores and when you have finished the workout your body needs to replenish this energy and it does so by accessing your fat stores to convert the stored fat to glycogen.

You could potentially burn 200kcals of fat from a 90 minute walk or conversely 200kcals from a 20minute HITT workout, which also has added fitness benefits.

Of course if you are trying to reduce body fat it is important not to reward yourself with a massive muffin post workout.  Even if you are not trying to reduce fat good nutrition is key to optimum health.

I tend to eat breakfast 90 to 60 mins before boot camp and is generally a mix of complex carbs and protein but nothing too fatty: my favourites are:

  • oat bran pancake, natural yogurt, berries, cinnamon
  • scrambled eggs, sourdough rye or spelt bread, grilled tomatoes
  • porridge with a spoonful of sugar free peanut butter and berries.

If you are running late grab something which is easy to digest such as a banana with oatcakes.

You can train your body to work on an empty stomach and this can be useful for endurance events such as long runs or triathlons, I do this myself occasionally to mix up my workouts.  It is hard and unless you have a reason to do so enjoy a lovely healthy breakfast.

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