December 28, 2017

Why You’re Not Losing Weight When You Run (And What To Do About It)

A lot of people run frequently but fail to achieve their weight loss goals. Here’s why.

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“I run regularly”.

“I watch what I eat”.

“And I can’t lose any weight”.

These are words directly from our client’s mouths. I’d like to say that I’ve heard this just once, but it is a common complaint I hear from many of the athletes who first join the Coached programme or visit our lab for testing.

Frankly, it’s a shame.

Despite wanting to improve and putting in the effort, their hard work is not being reflected in the results they are getting and their waistline remains unchanged.

Losing excess body fat is not the main focus when you join Coached but it is a by-product of following the training and nutritional advice in our programmes.

In this post, I am going to talk about a common roadblock that I encounter regularly that is affecting people’s ability to lose weight through running.

I will do my best to keep things simple but be warned, this post may be a little technical.

The Fat Burn Test

The graph below is the result of fat burn testing in our lab.


This test is essentially an x-ray for your metabolism where we’re looking at how you use your energy to determine whether you’re effectively able to generate energy from fat, or whether you’re reliant on sugar for the majority of your energy.

In an optimal scenario, high levels of fat should be burned at low to moderate intensities with sugar joining the party to fuel high-intensity training and racing.

As you can see in the graph, you burn fat in higher proportions at lower intensities and sugar in higher proportions at higher intensities.

If you’re running regularly and still not able to lose weight, it could be because you’re running too hard and are burning sugar rather than fat.

With the popularisation of the term calories and the ease of their measurement via our monitors, we have become obsessed with the idea that the more calories you burn, the better.

This is not necessarily the case.

Cut Race Times, Not Corners.

Racing at your potential and enjoying training is easy when you’re following the right programme.

Run Easier To Burn More Fat

To burn fat effectively, your body needs oxygen.

To ensure you are getting enough oxygen, you need to be running at a low enough intensity where that can comfortably happen.

A place devoid of excessive puffing.

Unfortunately, many runners are living in a grey zone where the intensity is not low enough to teach your body how to efficiently use fat for energy, although you can be burning a lot of (sugar) calories.

By slowing down, your body will get better at generating energy from fat and over time, you’ll be able to run faster ( and burn more calories) while maintaining the percentage of energy coming from fat.

To illustrate this point, take a look at the graph below.

This is the follow-up test to the one above after the athlete had slowed down in training, using a heart rate monitor to regulate his pace.


There are a few interesting observations that I would like to draw your attention to.

  1. Test protocols were the same for both tests.

  2. Fat burning stopped at the 13-minute mark in graph 1. In graph 2, fat burning stopped at a significantly higher speed at 18-minutes.

  3. Fat burning reached a peak of 34 grams/hour at the 6-minute mark in graph 1 before instantly starting to drop off. In graph 2, the fat burning peak reached 42 grams/hour at the 6-minute mark and was sustained at close to that level until the 13-minute mark (where fat burning had previously stopped).

  4. The crossover point (where the body goes from burning primarily fat to primarily sugar) happened at the 8-minute mark in graph 1 and the 14-minute mark in graph.

The Outcome

As you can see, that’s a significant improvement in fat burning ability. While the changes look cool graphically, you may be wondering what these changes contributed to in the real world?

A few things!

  1. A 45-minute improvement in the athlete’s marathon timing.
  2. A 7kg loss in weight.
  3. Faster recovery from training and racing.

In Closing

Today I have introduced a very common error that runners are making when it comes to fat burning and weight loss in running.

The good news is that it can be easily remedied.

There are other things that influence a person’s ability to generate energy from fat such as nutrition and stress. We’ll be touching on these in future posts.

For now, if you’ve been running regularly and are not seeing the loss of body fat that you are hoping for, it could be that you’re running too hard.

Try slowing down and see what happens.

To speed the process, do some of your running on an empty stomach. When sugar (the body’s quick fuel) is not as available, your body will get better at using fat.

If you’d like to learn more about your body and determine the state of your current fat burning ability, consider doing some metabolic testing to see how you’re using your energy.

Happy New Year!

I wish you and your loved ones a safe, healthy and happy 2018!

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Ben Pulham

Ben Pulham is the founder of Coached, a personalised training programme that helps runners & triathletes optimise, track and enjoy their training.