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  • Ollie McCarthy

Running for weight loss



“Running is the best way to lose weight right?”

Well no, probably not actually.

But it can be a useful tool if you do it right.



How to achieve weight loss


The basis of weight loss is a calorie deficit.

Which can be achieved through restriction of food (intake) or increase in movement/ exercise (output.)

Or a combination of the two.

Fundamentally your intake needs to be lower than your output so your body uses up it’s stores of energy (primarily body fat) and you lose weight.

Running can be a useful tool due to it’s high energy demand, which means it causes a high output (uses a lot of calories to run.)

However here are 3 things you may want to consider if you choose to use running as a tool to help with weight loss.

1- It will be very difficult to maintain performance while losing weight.

At first this probably won’t be a problem as you will have energy in your body to use, plus at some point running will be easier due to reduction in weight.

However, running is a energy demanding sport and if you aren’t fuelling your body properly, you won’t get favourable performance benefits that keeps many amateur runners going.

Over time as you deplete your energy stores further and have been in a calorie deficit for longer period of time, your performance will decrease.

My advice- either focus on weight loss and use running as a tool. Or focus on running performance and forget about weightloss. It’s likely you will still have some body composition changes regardless, as you adapt to the demands of running.

2- Cutting calories too low.

When losing weight you generally either want to use movement/ exercise to create a deficit or restrict food to create one.

Doing both is possible but can be complicated to manage. Plus it often ends up with you creating a huge calorie deficit.

Trying to run regularly while in a huge deficit is a recipe for disaster.

Firstly it will feel horrible as you are running with no fuel.

Secondly your performance will rapidly decrease, ( because you have no fuel) which will not help with your motivation to keep going.

Thirdly your risk of injury dramatically increases as your body can’t recover from the demands you’re placing on it.

My advice- unless you want awful runs and a higher risk of injury, don’t restrict your calories too much.

3- Cutting out carbs.

Fundamentally cutting carbs is just a method for weight loss, achieving its goal through the same way any other method works- a calorie deficit.

You see quick results because in reducing carbohydrate storage in your body, you also decrease water storage, which means you lose bodyweight fast.

However when you get past that initial quick weight loss, you will need to follow the same rules as everyone else- stay in a deficit.


And if you begin to eat carbs again, the weight will increase just as fast as it came off because you will begin to store more water in the body again.


Water storage is very different from fat storage by the way. But often the two get confused, which is why carbs get such a bad name.

Where running is concerned cutting carbs is an awful idea.

You main source of fuel is carbohydrate. And you need a well hydrated body to function.

So running on an under fuelled and under hydrated body is going to make running horrible.

So once again performance will decrease, as will motivation.

You may experience lethargy and brain fog (main source of fuel for you brain is carbs.)

And generally I think it’s just an awful idea- especially for runners.

My advice- don't cut carbs

So how do you actually achieve weight loss while running?

Well it's a difficult balance to strike. But as you can see from the above there are some things we can do to help the process.

Don’t cut out carbohydrates. Don’t reduce your calories too low. Don’t expect to be hitting any PBs.

Make sure you eat carbohydrates around and during your workouts to maintain performance.

And it you are someone who is performance driven why not work in phases.


One phase where you focus on weightloss while maintaining performance. The next phase work on improving performance while maintaining weight. This way you aren’t trying to do everything at the same time.


You will gradually decrease weight while maintaining performance which will keep motivation high plus you will see results on both fronts.





If you need any help navigating your running and weight loss feel free to drop me a message.


About the Author:



Hi my name is Ollie McCarthy and I am a Running Coach and Personal Trainer in Tunbridge Wells. I help people to build fit, robust and capable bodies that look good but also perform well. This is done through a combination of running, mobility, strength and conditioning work.



E: Ollie@mccarthysf.com


T: 07828573920

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