The goal of every cyclist is to optimize their power-to-weight ratio (w/kg). More power with less weight is going to make you faster —but how do you know if you are losing the right type of weight? Today’s post explores three methods cyclists can employ to measure their weight loss with precision.


Overview

Fat does a cyclist no favors when your power-to-weight ratio is concerned, but muscle certainly plays a key role. There are a number of ways to measure your body’s composition and get a breakdown of fat and muscle mass. With that in mind, my two Ask a Cycling Coach co-hosts and I set out to find which of these methods are easily accessible and reliable. Recently we tested three different methods of body composition and weight measurement. A few of the things we learned in the process came as a surprise. 

Skinfold Calipers

The tried and true method of measuring body fat is a skinfold caliper test. Chances are, all the body fat percentage-based maxims you’ve heard come from skinfold caliper tests. The best part about this form of measurement is it’s accessibility. Skinfold calipers are cheap and easy-to-use tools. 

The way this works is by measuring the thickness of your skin with skinfold calipers in specific locations on your body and then entering those measurements into a formula.

There are several methods that will have you measuring different regions than others, but the important thing is to stay consistent with your measurement method. In this case, we used this online tool to crunch the numbers.

Our measurement method had us measuring halfway between the nipple and top of the arm pit, one inch to the right of the belly button, and halfway between the knee and the hip. We would take each of these measurements three times, allowing at least 30 seconds between measuring in the same spot. Once we averaged the data out for each measurement spot, we entered the numbers into the equation on the site and got our estimated body fat percentage.

In most cases when skinfold calipers are used, athletic males will have 6-13% body fat while athletic females will have 14-20% body fat. A couple keys to getting consistent data are to measure in exactly the same place at the same time and under similar circumstances, and to use self-closing calipers. These will clamp down with consistent force, rather than relying on your hand to clamp down with exactly the same force each time. 

While skinfold caliper tests are accessible and can do a good job of estimating body fat, their downside is that they are immune to human error and only focus on the fat portion of your composition rather than your total makeup of fat and muscle.

DEXA (Dual Energy X-ray Absorptiometry) Scan

To get a much more comprehensive look at our bodies’ compositions we went to our local medical diagnostics center and underwent DEXA scans. If you’ve been keeping up with Ask a Cycling Coach then you’re probably already filled in on DEXA experiences. If you’ve missed those conversations, here’s the rundown: 

A DEXA scan paints a three dimensional image of your body’s composition that quantifies the fat, lean, bone and other mass components in your body. Separating it by quadrants of your torso and limbs, you are able to get a very clear picture of how much fat and how much muscle you truly have, as well as where your body stores that fat and muscle.

DEXA scans can be taken at many medical diagnostics and sports physiology centers and usually cost around $50.00 USD. In most cases you are required to fast overnight for the exam in order to get a better idea of your body’s true composition.

In terms of body fat analysis, the DEXA scan measures subcutaneous fat (like a skinfold caliper test) and visceral fat. The typical result is a body fat percentage that is roughly two times greater than the percentage indicated by skinfold calipers.

The true benefit of a DEXA scan is unlocked when you use it at regular intervals to track your weight loss and strength gains. For example, if your goal coming out of an off season is to lose that spare tire of belly fat and increase your core strength, you will be able to quantify your progress in terms of a decrease in fat mass and an increase in muscle mass in your trunk.

Cyclists often make the mistake of focusing on weight in general without paying attention to what type of weight they are losing. If they aren’t careful, radical dietary tactics can cause them to be losing muscle mass when their goal is to lose fat mass. The result would be decreased performance and increased potential for fatigue and burnout. DEXA scans can be a great tool to avoid this type of snafu.

Tanita

A much more accessible and eventually cheaper option is to use a Tanita Body Fat Scale. The way these function is by passing a gentle electric current via the scales’ metal foot sensors through your body to measure body fat. With this data it can estimate your total body fat percentage with surprising accuracy.

Most of these scales have four different persona profile combinations. Male and female, and athletic or average. We’ve found the athletic setting to align very closely with the skinfold caliper data while the average setting is very similar to the data from the DEXA scan. We’re not sure what this says about the profiling built into these scales, but the important thing is that they align very closely with a widely accepted form of body fat analysis and a scientific and thorough form of measurement.

When you step on the scale, you simply define your age, gender, activity profile, then let the scale measure your weight and estimate your body fat percentage. While basic scales can be purchased for around $70 USD stop there, some of the more advanced scales for $150 USD that can do a surprisingly accurate job of estimating lean mass as well.

Having one of these scales to step on every day can be a massively effective tool for cyclists who are watching their power-to-weight ratio. Once again, the same caveats exist here as with other forms of body fat analysis. Always measure under similar circumstances, making sure the time of day is similar, that you are not wearing any clothing and that your nutrition and hydration leading up to the time of measurement are accounted for if not controlled.


Listen to Certified Cycling Coaches Discuss Weight Loss

Weight loss is just one topic we covered in episode 31 of the Ask a Cycling Coach podcast. Listen to the episode’s full recording below to hear this and other questions from cyclists get answered by our certified cycling coaches.



Additional Notes

TrainerRoad’s Ask a Cycling Coach podcast is dedicated to making you a faster cyclist. It gives you the chance to get answers to your cycling and triathlon training questions from USAC certified coaches Chad Timmerman, Jonathan Lee and special guests. Learn more about other topics we covered in the latest episode with our resources below:

  • How to measure body fat
  • Weight loss for cyclists
  • How to train for a short time trial
  • How to pace a time trial
  • How to recover after a workout
  • How to know when you should bridge to a breakaway
  • Race tactics for cyclists
  • How to establish a breakaway
  • How to judge a race
  • What is the ideal weight for a triathlete?
  • How to pace a half-ironman
  • Is lighter always faster for cyclists?
  • How to train for single speed racing
  • How to train for Leadville

If you have a question that you’d like to ask Coach Chad, submit your question here. We’ll do our best to answer them on the next episode of the Ask a Cycling Coach podcast.



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Jonathan Lee

Jonathan Lee is a Level II USA certified cycling coach and the host of the Ask a Cycling Coach podcast. His background in the sport of motocross has translated into a passion for cycling, mountain biking and all things training. If you have a training question, submit your question for Jonathan to answer on the next episode of TrainerRoad’s podcast.

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