Running for weight loss seems like the most natural thing in the world.
Running is one of the most accessible and popular forms of exercise on planet, and a super efficient way to burn a lot of calories in a short period. So it’s a no brainier for weight loss right??
In this post we’ll look at why running doesn’t always work for weight loss and why its still a good idea when it doesn’t.
Running for Weight Loss Doesn’t Always Work
There is a mountain of evidence suggesting running can be good for your your health, but it doesn’t guarantee fat loss. In fact it can be a breathtakingly inefficient way to go about it, because it often causes hunger that makes you eat back extra energy used.
In the chart below I’ve graphed the bodyweight and fat percentage change from a study where 400 middle aged women were randomised into groups where they did zero (control), one hour, two hours or three hours of cardio per week for 6 months at around 50% of their maximal heart rate. This cardio was a mix running on a treadmill and using an elliptical.
In this study they found no significant differences in weight or body fat percentage across the groups. The more exercise the women did the better it was for their fitness and health markers, but the scale barely budged. Sp across four groups of 100 middle aged women who did either 0, 330, 660 or 1,000 kcal/week of exercise over six months they could find no statistically significant difference in body composition.
Now, I need to point out that this is just a single study. There are also plenty of cardio interventions where that have been shown to promote significant fat loss. But you’d be a fool to think that just because you start running it means the weight will automatically fall off. Indeed for some people running is such a significant hunger cue that it causes weight gain.
Running for Weight Loss Can Work
A good counter example is a 2013 study where they paid individuals $8/hour to do 5×400 kcal or 5×600 kcal of treadmill running each week. In this case the target intensity went from from 70% to 80% of maximal heart rate as the trainees got fitter.
This is very different to our earlier study where the target heart rate was 50%. In this case people were really running! With both higher volume and intensity on their side the results looked very different.
Both of the exercise groups produced significant fat loss with the higher volume group losing an impressive 5.2 kg (11 lbs). Both groups also improved their aerobic fitness, as you might expect. Impressively all fat free mass was conserved.
The most interesting finding was that if you looked at the individuals there was huge variation in the results, with some people losing over 10% of their body weight and other barely budging. This to me is a clear indication of how much people’s hunger response to cardio can vary a lot.
I think this second study makes a good case for the benefits of higher intensity running when it comes to fat loss. But all the same the key takeaway needs to be much broader than run faster for fat loss.
You see your fat stores don’t really care how far you ran today. They care about what your deficit is. Running can be a strategic part of creating that deficit, but the deficit itself will always be determined by what you put in your mouth. So best to work out a strategy to control your what you at before you start running.
Running Is Incredibly Healthy
A few years ago a series of papers highlighted the potential dangers to the heart of excessive endurance training (think ultramarathons and ironmans). To assess these risks researchers decided to look to see if there if they could find a threshold where fitness actually begins to increase your risk of dying, instead of improving it.
Here’s what they found.
Among the 38,000 people who were reasonable fit (METS>10) they simply couldn’t find a point where there stopped being a mortality benefit to fitness. The fitter people are the less and less likely they are to die soon.
Based on the evidence it’s simply foolish to assume that running will automatically make you lose weight. If you would like to use running as part of a weight loss program make sure you have an effective diet strategy in place first and work to build up intensity as you progress. Moreover, don’t forget that even if your fat loss results aren’t what you’d hope for that running will e doing wonders for the health of your heart and lungs.