When to workout whilst intermittent fasting

When to workout whilst intermittent fasting

When intermittent fasting the question of when to train around meal times is a big one and there are a lot of factors that it depends upon.  Everyone will have a different piece of advice for you but here are a few things you should consider. 

What times do you fast and for how long?

There are multiple ways of doing intermittent fasting so the timings you choose to fast help to dictate the times that you should train around that.  You don't want to train on a full stomach but you might want to train fasted to get better results in fat burning. 

Training while in a fasted state has been a popular tool for people trying to lose weight for years. Your body primarily uses glycogen or stored carbohydrates to fuel exercise.  It's suggested that when your glycogen stores are depleted, which occurs after a fasted period, your body is forced to use other energy sources such as fat. 

What is your goal? 

If your goal is weight loss, then training fasted can be a good thing for you.  If not, training fasted could be detrimental to your goals.  It could help to target the fat store for fuel but fat stores are not the only fuel for your body, it also uses proteins (your muscles) for energy. 

If you are low in calories your body wants to be more efficient and can eat away at your muscles mass so there is not so much of you to power.  Over time this can drop your resting metabolic rate as well as reduce your strength gains and ability to build muscle. 

If you are training for an endurance event and going for a long workout you are likely to hit a wall sooner if you are fasted as you won't have the energy stores needed to maintain the workout.  Your performance is likely to drop and you won't be able to workout as well.

What times are you available to train?

  • If you can only train in the morning before work this will affect what type of intermittent fasting you do and when you train and eat. 
  • If you can only train in the morning before work then you are likely to train fasted as its harder to get a meal in before you train.
  • If you can only train in the evening your workout is more likely to be non-fasted as you would have eaten during the day. 

Whether you prefer to train on an empty stomach? Some people can't train on an empty stomach and it makes them feel sick. Others would naturally train fasted anyway. 

So working out before the eating window is ideal for someone who performs well during exercise on an empty stomach, while during the window is better suited for someone who doesn’t like to exercise on an empty stomach.

How much of a gap should you leave to train after eating?

Everyone is different so listen to your body and go with how you feel but as a rough guide - if you want to build muscle i would suggest eating a snack around 30mins before your workout to help keep the glycogen stores up and fuel your workout. 

I would leave two hours after a heavy meal before you train as it can slow you down and leave you feeling sluggish.  Exercising on a full stomach can also cause indigestion.

If you are keen to burn fat a fasted workout may suit you better so try not to eat anything for 4 hours or more before you train. 


Intermittent fasting is commonly used as a tool to have reduced calorie intake and to help people lose fat.  But remember if your goal is to keep gaining muscles and building strength you may want to make sure you have had enough calorie intake to support this. 

To summarise make sure it works for you. We are all different and our bodies are as well so play around with it and try a few things to see how you feel.

Aaron Collins-Thomas

Founder of TONIQ


When do you workout best? Let us know in the comments below. Share this with someone who you know would benefit from reading this. The U Perform family loves sharing ideas and encouraging each other.