Determining Your Race Weight

The latest article from our Director of Training, Michael Donnelly.

Last month, I talked about general nutritional guidelines for endurance training. This month, I want to talk about determining your race weight. Being too heavy is detrimental for running and being too light is detrimental for swimming and biking. The funny thing about race weight is that you will know what it is once you get in great shape and race well.

Race weight is the weight at which you are at optimal body fat. Optimal body fat varies based on gender, age, competition level and length of race. The following table from ACSM presents optimal body fat ranges (very lean – good).

Age Group Women Men
20 – 29 11 – 20% 4 – 15%
30 -39 11 - 21% 7 – 18%
40 – 49 12 – 24% 9 - 21%
50 - 59 14 – 27% 11 – 22%
60 - 69 14 – 28% 12 – 23%

Determining your body fat percentage can be found by utilizing a device (e.g. calipers, hand-held monitors, scales, etc.), however it is best determined with the help of a Registered Dietician or qualified fitness specialist. My suggestion is to get an inexpensive scale (e.g. Tanita Ironman scale) or hand-held device (e.g. Omron hand held scale) and find your current percentage of body fat. The next step is to determine how much fat weight you need to lose to get to your racing weight. Here are the steps and an example to follow.

1. Determine current body fat percentage. 
• For example; a 50-year-old male who weighs 160 pounds used the Omron hand held scale and determined his body fat percentage to be 20%.

2. Calculate your body fat mass. 
• Body fat mass = current weight x current body fat percentage
• 32 lbs. = 160 lbs. x .20

3. Calculate lean body mass.
• Lean body mass = current weight – body fat mass.
• 128 lbs. = 160 lbs. – 32 lbs.

4. Calculate your goal weight.
• For example; this athlete set a goal to attain a 16% body fat percentage (half-way between very lean and good per the chart above).
• Goal weight = lean body mass / (1 - goal body fat percentage)
• Goal weight = 128 lbs. / (1 - .16)
• 152 lbs. = 128 / .84
• This athlete will need to lose approximately 8 pounds to get to his race weight of 152 pounds.

Additionally, here are some things to remember that will help you get to your racing weight.

• Fat loss should never exceed 1 – 1.5 pounds per week. Try to consume 300 – 500 fewer calories per day than your body burns. This small daily calorie deficit will yield big results during the off season.

• You never want to be at race weight too early in the season. Being at race weight is stressful for your body and can compromise your immune system. Being above race weight during the off season allows your hormone levels to recover and helps your body to repair soft tissue that was damaged during training / racing.

• Never cut calories from your workout or recovery. Please refer to last month’s coaching newsletter for nutrition guidelines.

• Only weigh yourself once a week since body weight will fluctuate day to day.

• Focus on performance, not fat loss. Periodically complete swim, bike and run tests to ensure that you are getting faster as you get leaner.

• Try to develop a habit of eating until you are comfortably full and then stopping, even if there is food left on your plate.

Most importantly, be healthy. None of us are getting paid to race so the most important thing to remember is to stay healthy.

USAT Level 2 Endurance Coach
ACSM Certified Personal Trainer
Total Immersion Certified Coach