Will losing weight help you run faster?

As a sports dietitian who specializes in working with endurance athletes, especially runners, I have heard more than once from potential clients “I would like to improve my running, and if I could lose weight that would be a plus.”

As I dive deeper into my conversations with these potential clients, I realize that one of the underlying questions is, “Will losing weight help me run faster?”.

The thought process behind the answer to this question can be explained in two ways: physics of running and VO2 max. Running is a series of forward and upward movements that directly fight against gravity with each stride. So your’e thinking isn’t wrong that the higher the body weight, the more work it is to fight against gravity thus potentially slowing your pace. 

Another way to look at how bodyweight impacts speed is to examine VO2 max, or the maximum amount of oxygen your body can process to produce energy. A high VO2 max is similar to having a larger car engine, it gives you more energy potential. VO2 max and body fat are inversely related, meaning the higher body fat you have, the lower your relative VO2 max will be. However, it should be noted that VO2 max is not an end-all measurement of fitness or running speed. 

To bring it back to the question at hand, can weight loss equate to increased running speed? The answer is, it depends. I know, probably not the answer you wanted to hear. But like most topics in nutrition, it is not black and white and there is not one size that fits all. Not everyone that loses weight will have increased speed, and it can come with detrimental effects. If you are an experienced runner and lose a modest amount of weight, it may improve your running speed by improving your VO2 max. However, if you have a larger bodyweight or are a new runner it is a different story. You may think losing weight will improve speed, but it can actually sacrifice performance by putting the body in a state of scarcity. When fat loss occurs whether fast or slow, you are bound to also lose some muscle as well. Which can result in a decreased Resting Metabolic Rate (RMR), the rate your body burns energy at rest. This can be exacerbated if you are restricting calories and together this can mimic a starvation response. A body in a starvation state will hold onto fat as a protective measure and will break down muscle for energy leading to increased risk of energy and illness. 

You are more likely to improve your performance by focusing on proper nutrition and consistent training versus focusing on weight loss to achieve an arbitrary number while putting yourself at risk of injury and muscle breakdown.

When it comes to weight loss for runners, there are no clear-cut answers, and is why it is important to work with a dietitian who has experience working with runners and/or atheltes. It is also important to be kind to yourself. Everyone has a different health weight range where you perform your best, whether competing or speaking generally. Unfortunately, this weight may not match what you picture for yourself or what society tells you to look like.

If you find yourself gaining weight while increasing your training (strength and cardio) and eating a balanced diet, you might be gaining weight from increased muscle. Remember, the number on a scale is just one measurement of your body. Weight itself does not take into consideration body fat percentage and muscle mass. Muscle weighs more than fat, so if in fact you are gaining muscle and losing fat, this means you are improving your glycogen storage and that is a positive thing for running performance.

If reasonable weight loss is a high priority for purposes other than increasing speed, it is a good idea to do that in your off-season training to avoid losing too much weight and end up injured, sick or decreasing running performance. 

Side note: Instead of setting your focus on weight, rethink your shoe choice to increase speed. Heavy limbs are harder to move than a heavy torso, and losing weight from your body is about 30% as effective as losing weight from your shoes which means extra shoe weight requires more energy to haul forward than abdominal fat.

When it comes to running speed, often there is not a silver bullet solution for improvement. It is multifactorial and is impacted by more things than just your body weight. Behind every amazing run is typically proper nourishment, a good night’s sleep, stress management and strategy. If you are someone who is seeking to improve your performance and endurance, reach out to me!