Fasted or Non-Fasted Training – When should I Eat?


People often ask me if they should eat before they exercise. It really depends on what you are trying to achieve and what sort of exercise you will be doing.

There are benefits to both fasted and non fasted training and I personally believe that whatever you are trying to achieve you should try and incorporate a mix of the two.

Fasted Training

I class fasted training as exercising when I haven’t eaten for 12 hours. The easiest way to do this is to make the session first thing in the morning so that you have slept through most of the fast.  For example if you are going to train at 6 am, don’t eat anything after 6pm the night before.

A fasted training session should be relatively easy and not more than an hour in duration. An example of this would be a 45 minute slow run, a brisk walk or an easy spin on the bike as opposed to a tempo session.  Your breathing should be controlled and you should be easily able to hold a conversation.

What are the benefits to fasted training?

Because your body is not fueled it has to tap into its fat reserves to feed the training session, therefore burning body fat.

If you are training for an endurance event it teaches the body to use fat as fuel so that when you get to the point in your event that your body has used up all its carbohydrate stores it can more easily switch to fat burning mode.

Sounds great, why don’t I do this all the time?

Because it reduces performance. Without fuel you cannot train to your full potential so you will not be reaching full fitness.  Remember that a fasted session should be easy – you need to do some intense sessions to build fitness, get faster and they also burn body fat too.

There are 4 circumstances I can think of when I would not do fasted training:

  1. If the training session is weight training
  2. If the training session is high intensity
  3. If the training session is longer than 1 hour
  4. If you are diabetic or suffer with low blood sugar (in this instance you should consult your nurse or doctor)

Non-fasted Training

Think about your car.  Without enough fuel in the tank it does not perform very well if at all. Your body is the same!  During a fueled training session you can work hard, increasing your strength and fitness and burning a higher number of calories.  These gains will also increase the amount of calories you burn at rest. Therefore non-fasted training is an important part of the mix.

How many times a week should I do a fasted session?

There are no hard and fast rules here but I would say, if you are training to lose weight about 25% of your training could be fasted.

If you are training for specific events then just 1-2 sessions in the week could be fasted

The points raised in this article are just my opinion and its what I actually do.  For some people it may not work, for others it may. But I hope that it has highlighted that whatever you do variety is important!






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