It has been said that 4 factors determine how fast you are – genetics, form, how smart and hard you train and weight (not necessarily in this order). Every runner knows weight affects performance. As a general rule of thumb, lighter does equal faster. However, we must always remember too much of anything is always detrimental.


You move up during running, and this means moving against gravity. Basically, the more mass an object has, the more force you need to accelerate it. In laymen terms this just means, the lighter you are the less force you require to move yourself forward. The caveat to this is that being too light may cause your health to suffer. Hence there notion of the ideal racing weight, and not to be as light as possible.


Basically, assuming all other factors are equal, you will race faster the lighter you are without compromising your health.

So, What Is Your Ideal Racing Weight?

There is a theory that racing weight is affected primarily by body fat level. There isn’t much you can do about the other sources of masses in your body – bones, water, muscle. These levels tend to stay the same. So it is this body fat you must lose in order to attain your ideal racing weight.

The Basics

The level of ideal body fat in men and women differ. Men generally have a lower body fat percentage as compared to women. This is because at some point of their lives, they would need to nourish a baby and hence the fat reserves.

The ideal body fat percentage level for men aged 20 – 29 is 3 – 10 percent. Men aged 30 – 39 should fall within 5 – 12 percent whereas men aged 40 – 49 should fall within the 6 – 15 percent range. Men aged 50 and above – 8 – 17 percent.

For women on the other hand, women aged 20 – 29 should have a body fat percentage of 10 – 16 percent, 30 – 39 should have 11 – 17 percent whereas 40 – 49 should fall within the 13 – 20 percent range. Women above 50 should keep to the 14 – 22 percent range.

This gives you a gauge on what your ideal weight should be or how much weigh you need to lose.

The Mathematical Formulae

For instance, if you are a female 25 years of age weighing 60 kilograms with a body fat percentage level of 20 percent. This means you have 12 kg of body fat and 48 kg of lean mass. As your ideal body fat levels should be at least 16 percent, your lean body mass percentage should be 100 – 16 = 84 percent.

The formulae for your goal weight would be = lean body mass divided by your goal lean body mass percentage. Hence your ideal body weight should be 57.1kg. You would need to lose 3kg to hit your ideal racing weight.


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