Will I run faster the more weight I lose?

Will I run faster the more weight I lose?

It’s finally running season again, and whether you’re training for a full marathon or you’re just a casual runner it’s good to know what you can do to improve your overall speed.


Losing weight can make you a faster runner, but this will vary drastically depending on how fit you already are.


Being leaner can make you a meaner runner

VO2 Max, or the maximum amount of oxygen a runner can use within a certain time per unit body mass, is one technical way of measuring a runner’s fitness. The lighter a runner is at a given fitness level, the higher his/her VO2 Max will be, and, theoretically, the faster he/she will be.


Running experts say losing one pound can reduce your time by a couple seconds for each kilometre you run. Losing ten pounds can shave about a minute off of your normal 5K time, and more than two minutes in a 10K race.


Losing muscle mass will actually slow you down

While dropping a couple pounds of fat will improve your race time, losing muscle can hurt your overall performance. Muscle loss occurs when you’re burning more calories than your body needs to perform properly. Your body will use its muscle as an alternative source of energy, which in turn makes you weak. Losing muscle can also slow your metabolism.


Sprinters and long-distance runners have different needs

If you want to be a faster sprinter then building muscle may be more advantageous than trying to lose weight. Being heavier allows you to run with more power and cut through wind. Long-distance runners are generally on the leaner side though and benefit from weighing less. 


If you’re looking to improve your overall speed, losing weight can help. But it’s equally important to follow a proper diet (which includes carbs and proteins), drink lots of water and combine your runs with strength training.  


Lose Weight, Gain Speed

This table, based on changes in maximal aerobic capacity, provides a rough estimate of how much your race times will improve if you lose weight, as long as you have it to lose. If your BMI drops below 18.5, you’re at risk of becoming weaker and slower.






2 lbs

12.4 secs

25 secs


52 secs



5 lbs

31 secs






10 lbs








20 lbs









Via Runner’s World 









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