BIA measures the impedance of this circuit, or how much the tissue resists the electrical current that passes through it. Using the height of the person, the total body water (TBW) can be calculated, and from there, fat-free mass (FFM). Subtracting FFM from total body mass gives fat mass (FM). However, height isn’t enough to get an accurate measurement, since the human body isn’t a perfect cylinder. Laboratory BIA equipment uses a five-cylinder model (arms, legs, and torso), but that means you need to attach electrodes all over your body. AURA uses a novel two truncated cones (TTC) model for the arms as a nice balance to take convenient measurements with the hands without sacrificing too much accuracy. How accurate is BIA? The actual app is pretty well-designed and easy to understand. That’s true of both the iPhone and the Apple Watch versions of the app. On the iPhone, you’ll get a “Body” tab, which shows you a breakdown of all your latest measurements, allowing you to tap on each metric for more information. I did have some issues taking my first reading. After uninstalling and re-installing the apps, and restarting both my phone and watch, I was still unable to take a reading. After I took the battery out of the Aura Strap and re-installed it, I was able to take my first reading successfully. But these issues turned out to be a common occurrence for me. Using the Aura Strap 2 A: If you want fairly accurate fat, hydration, muscle and other body composition metrics then Aura Strap 2 is a good call. Alternatives like smart scales are restrictive and similarly costly. The gold standard DEXA scan is a one-off and very expensive lab-based alternative.

A: Yes Aura works with any Watch from Apple Watches Series 3 to Series 7, and with 38/40/41 and 42/44/45 mm Watch sizes. Aura also gives you the option to set their watch face and that makes use of the complications which you are free to use on any Apple Watch watchface. The complications available are the latest results for water, muscle and fat. My body type is determined by Aura, whereas I set my own goal within the app which is to gain muscle. Aura gives me various generic strategies to achieve that goal like ‘ do more weights and eat more protein‘.

Aura strap 2 works with all Apple Watches from Series 3 and is available in two sizes each accommodating 38/40/41mm and 42/44/45mm Watches. By performing bioelectrical impedance analysis (BIA), which measures how a person’s body changes as a result of exercise, AURA Strap 2 is the only wearable device that provides fat, muscle and water balance measurement on the Apple Watch. From there, via AURA App version 3.0, users receive insights, personalized recommendations and goal setting and management functions to assist them in optimizing their fitness performance.

The Aura Biogram is a cool tool to graphically show your progress toward your body composition goal. The Apple Watch app is basically a stripped-down version of the “Body” tab in the iPhone app. You’ll get a rundown of each recent measurement, and tapping each measurement will show you an explanation of what’s being measured. Hydration: Aura had me more hydrated than Garmin which in turn showed greater hydration than Tanita. Despite that, the Aura reading is in the middle or lower middle of what Aura says to be the average range for the population. There were noticeable variations in the hydration level reported by Aura when there should be ie if I had been diligently taking more water/isotonic drinks than normal or if I was dehydrated after a sweaty, summer 90-minute run.For some comparison tests, I used an old Tanita RD953 scale and a newish Garmin Index S2 smart scale. Even using those two comparator devices poses problems right from the start. Aura sends its electrical signal down one arm across the chest and down the other arm, whereas Garmin does a similar thing but its loop is from one foot to the other via your core. Finally, Tanita does a combination of readings with a sensor on each of the feet andhands.

To me, the price of the Strap seems good but I’m less sure about the cost of the subscription unless there are aspects of the app that you can immerse yourself in over longer periods. Other than the workouts, available elsewhere, I just don’t see that ongoing level of value. You might of course. It’s common knowledge that the body is made mostly of water, and that water containing impurities (i.e., almost all water) conducts electricity. But there’s an important difference between water that’s inside the cells (intracellular water, or ICW) and water that’s outside the cells (extracellular water, or ECW). Cell membranes are very poor conductors, so the water inside and outside, separated by the membrane insulator, together create a natural capacitor. Therefore, a low-frequency alternating current (AC) can flow through ECW but can’t reach ICW, whereas a high-frequency current can pass through the membranes and into ICW as well. This natural feature of body tissue can be described just like a simple parallel electrical circuit with resistors on both branches (the ECW and ICW), and a capacitor on the ICW branch: Whilst the mechanics of taking a reading is mildly cumbersome, that very short inconvenience is offset by the ease at which you can get these readings anytime or anywhere. Smart bathroom scales might be an alternative but they are just a little less portable!

To truly maximize the benefits of AURA Strap 2, the new AURA Plus subscription service provides members more resources and features, including monthly fitness and nutrition reports, deep analytics of body composition, exclusive fitness content and – coming soon – a live chat function with a personal trainer. You have full control over what information the Aura app can read from your phone or write to it. Using the normal sync to Apple Health, you might want to enable everything except, perhaps, the ability of Aura to write your weight to the phone. Bearing in mind that I’m definitely significantly both musclier and ‘fatter’ on my legs than my upper body and that the readings might reflect that, let’s see what I found. Aura Plus users get more details like exercise & diet recommendations, suggested workouts, and deeper analyses.