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Withings Smart Body Analyzer WS-50

Withings introduced its Smart Body Analyzer WS-50 earlier this year and made it available to the public in mid-March. We came across it by an accident when looking to purchase a new scale but not necessarily a smart one. In the past, we have been occasionally using Omron’s s smart scale purchased some five years ago. While we have liked several of its features, we have always found it somewhat cumbersome to use both in terms of its user interface and very limited possibilities for storing and tracking past measurements. While that may or may not be different with Omron’s latest offerings, we decided to go for Withings. Over the past two weeks, we have been using it on a daily basis.

Industrial design meets pleasing user interface
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The front fascia of WS-50 is made of nice looking tapered glass making the scale at the same time both discreet and visually pleasing. WS-50 is designed to measure and monitor:

- Weight
- Body fat
- Heart rate
- Air quality (ambient temperature and carbon dioxide level)

WS-50 features 802.11b/g/n and Bluetooth connectivity and has an accompanied Health Mate app for iOS (iPhone, no dedicated iPad app currently available) and Android for tracking and visualising measurements.

Exceptionally simple to set up and use
Removing the WS-50 from its box, the installation was a simplicity in itself. Pushing the button at the bottom of the scale established a Bluetooth connection with our iPhone 5. Thereafter the Health Mate app and scale’s display guided through a few easy steps to finalise the setup process and establish connection with our Withings account that we had opened already prior to receiving the scale. Finally, the app asked for a permission to share our iPhone’s Wi-Fi settings with the scale in order to establish a Wi-Fi connection for uploading measurements to the Withings cloud. After setting up the Wi-Fi connection, the Bluetooth connection can be switched off.

We have been very satisfied by WS-50, not least because of its ease of use. All measurements are automated and start by stepping on the scale. WS-50 has supports up to eight individual users and has an automatic user recognition based on weight. New users can be easily added via the Health Mate app.

Because we don’t have any other temperature meter, we have found it informative to see our room temperature. In less than well ventilated bedrooms, being able to monitor carbon dioxide levels may also be useful. WS-50 automatically performs temperature and carbon dioxide measurements every 30 minutes. All readings are automatically uploaded to the Withings cloud and synced with the Health Mate app at least once a day or every time when a body measurement process is performed.

The scale itself also shows current data on its display while performing measurements. All records can be later tracked both using the Health Mate app or the Withings web interface on any computer. We prefer the Health Mate app that is visually clear, pleasing and easy to use. The app made the data available both as numbers and charts. Finally, extrovert users can choose to share their measurements via email, Twitter or Facebook.

How accurate are body fat measurements?
For most people, being able to measure body fat is likely the most interesting feature of any smart scale. As usual with consumer smart scales, fat measurements are performed using electrical impedance analysis. According to Withings, “its working relies on injecting a very low intensity current into the feet, and the simultaneous measurement of electrical resistance met by this current. As the fatty tissue is not a conductor, the resistance is in proportion to the quantity of the body's lean mass. Several equations are used to deduct the lean mass, then you calculate the quantity of body fat by subtracting the lean mass from the total weight.“

In useful tips available on the Withings web interface, the manufacturer recommends taking measurements about 30 minutes after waking up in the morning in order to avoid weight variations during the day due to diet, digestion and physical activity. For example, dehydration is known to increase the body’s electrical resistance and thus lead to an overestimation of the body fat. Conversely, body fat measurements tend to be too low if recorded after a physical exercise or a meal. Overall, it is commonly perceived that the electrical impedance analysis method for measuring body fat is useful for tracking body fat development over longer time periods but not a too reliable method for a single point measurement.

Unfortunately, we can’t comment on absolute accuracy of WS-50’s body fat measurement from our own experience. However, we have noted that taking measurements in the morning immediately after getting up from the bed often generates clearly skewed (2-3 %-points too low) body fat results. Repeating measurements only some 15-20 minutes later has so far every time given results that have been consistent both in day to day comparisons and relative to measurements taken late at nights. On the basis of our short two-week experience with the WS-50 it indeed seems important not to measure body fat immediately after getting up in the morning but rather some 20-30 minutes later but before the breakfast.

Recommended for those looking for a smart scale
Worthwhile alternative for those looking for a smart scale.
Most active people can live happily without a smart scale while some will find it either interesting or outright useful being able to track body fat as well as some other parameters monitored by smart scales. Both easy to set up and pleasure to use, we regard nicely designed Withings Smart Body Analyzer WS-50 as a worthwhile option for those looking for a smart scale.