By Joshua Cohen
We all know it costs more to take weight off a bike than off your body. And if you actually look at the numbers, the difference can be staggering.
For example, the cost of upgrading to a lighter crankset can be as much as $2.50 per gram. Considering that there are 448 grams in a pound, a pound of crank weight saved is worth about $1,120!
Of course, you could argue that there are less costly component upgrades, and that rotating mass is more significant than static mass. But the bottom line is that the cheapest way to reduce your bike + rider weight is to lay off that $5 box of doughnuts.
Although shedding body weight may be the cheapest way to lose a few pounds, it’s definitely not the easiest. To make matters more complicated, studies suggest that lowering overall body weight may actually increase mortality risk, while
losing just fat can decrease mortality risk. This highlights the importance of tracking body fat percentage when you are on a weight-loss diet to ensure you are losing fat instead of water or muscle weight.
The Tanita BC590BT body composition scale not only measures your total weight and body fat percentage, it also gives values for:
- body water percentage
- muscle mass
- physique rating
- daily caloric requirement
- metabolic age
- bone mass
- visceral fat
(The daily caloric requirement is an estimate of how many calories are needed to maintain your current weight based on activity level.)
There are other scales that measure at least some of these values, but the Tanita BC590BT does all this and it wirelessly uploads data via Blue Tooth to the Healthy Edge software (included) on your computer.
The software allows you to create different users, graph trends in any of the above categories, and see readouts of all of these values. You can also view the values on the scale without uploading data.
Bone Mass Evaluation
Bone health in cyclists has been a big issue at RBR and this Tanita provides a “bone mass” value to use as you please.
Note that a scale like this can only directly determine a person’s weight and bioelectrical impedance. All other readings are indirect measurements based on researched algorithms (the user inputs age and height). For example, many studies have looked
at the association between age, weight and osteoporosis, and have found statistical correlations to link the variables.
Bioelectrical impedance has been demonstrated to correlate with bone mineral density measurements. It did not, however,
“enhance the ability to diagnose osteoporosis significantly compared with simple clinical criteria such as age and weight” (Journal of Bone and Mineral Metabolism).
Tanita does not actually provide standards for bone mass, according to a company spokesperson. “Setting a standard may encourage users to judge the possibility of bone-thinning osteoporosis, bone fracture or other disorders,” she says. “However, judging
bone status is a medical act. This [scale] is not designed to make such judgments.”
At any rate, I would be skeptical of using a scale such as this to evaluate the bone mass of a younger, athletic person because this does not appear to be the population on which most studies are based.
Setting up this Tanita is relatively easy. You input your age, height and activity level into the scale itself. It can store data for as many as 4 users. Then you install the Healthy Edge software and the Blue Tooth USB toggle and drivers.
To upload a new scale reading, simply click the “new scale measurement” button in the Healthy Edge software, push another button on the scale, and step on to get weighed. Then the software stores your data for later analysis (see screen shots below).
The Bluetooth transmitter theoretically can send the data from another room, but I found that thick walls interrupt the signal and prevent the scale from pairing with the computer.
My body fat percentage varied widely, depending on whether I qualified as an “athlete” when entering my personal data into the scale. Tanita’s definition of an athlete is someone who works out 10 or more hours per week. I average 8 hours so I didn’t choose
the athlete option. This raised my body fat by 7 percentage points.
The software does not make it easy to pick out measurements based on time of day, so it is important to take daily measurements at the same time and in the same conditions. I didn’t initially, and my graphs showed wide fluctuations due to hydration levels
and food intake.
After running in high heat for 2 hours and losing 5.4 lbs. (2.5 kg) of water weight (I should have taken more fluids), I was discouraged that this Tanita told me I had lost 2% body fat and gained 1.6% body water. This obviously was not the case.
The Healthy Edge software is able to track data from pedometers, blood pressure monitors and more advanced Tanita scales. The software offers many graphs and charts to show how your measurements align with accepted ranges and where you are compared to
your goals. I would like to see a way to filter the data based on time of day, making it easier to compare only similar conditions.
I was also disappointed to find that the Tanita’s data can’t be uploaded to the popular, free Sport Tracks software, which quite a few people use to log exercise sessions.
Whether you want to gain, maintain or lose pounds, it is useful to keep track of your weight over time.
The Tanita BC590BT makes it easy to upload data and produce graphs that help you track weight and body fat trends. Despite some published research that suggests a scale’s calculation of body fat percentage is accurate, I feel it’s
best to track trends, not absolute values, and always take measurements under similar conditions to improve validity. I question whether this type of scale can accurately monitor hydration levels, so I would not use it to determine dehydration from cycling
— other than to compare pre- and post-ride weight.
At $250, the BC590BT costs around $200 more than other Tanita scales that also measure weight, body fat percentage and hydration percentage. For the extra $200 you get the Healthy Edge software, Blue Tooth data upload, and some additional measurements
that may or may not be useful to you.
Screen from Tanita’s Healthy Edge software:
Joshua Cohen is a physical therapist and designer of the Kontact Saddle. He wrote his graduate thesis on male ergonomic bicycle seat design. Then, distilling his voluminous scholarly research, he wrote Finding the Perfect Bicycle Seat and, more recently, The Illustrated Guide to Bicycle Seats. Both eBooks are available in the RBR eBookstore.