Can The Amazon Halo Wrist Band Provide Useful Information on Body Fat and Sleep Quality?

The skeptical cardiologist has been on a quest to find ways to easily and accurately measure sleep quality and body fat, two parameters which significantly influence cardiovascular outcomes. I’ve been disappointed in every sleep tracker I’ve evaluated (see here for my Oura ring analysis) and all but one method for measuring body fat (see here.)

During a recent telehealth visit with one of my patients who utilizes both Apple Watch and Kardia to monitor his cardiac rhythm, the discussion segued into sleep tracking and body fat measurement with a new fitness band from Amazon he had evaluated, the Halo.

I was heretofore unaware of Amazon’s entry into the wearable fitness device market but its Halo touts quite a few capabilities which, if accurate, might be of great value to my patients.

I asked my patient to provide my readers with his evaluation of the Halo. What follows is his assessment followed by my observations on the ideal method for body fat measurement.

Initial Thoughts on the Amazon Halo

I was able to get an early version of the Amazon Halo through the Early Access program. (Editor’s note-this program is ongoing and allows purchase of the Halo for $64.99 versus $99 when the program ends. Note that you are auto subscribed to membership at $3.99 per month which enables the app functions.)

The Halo is a very simple wrist band that can track your movement, pulse rate and your tone of voice.  The device is essentially passive, other than requiring a button press to activate the microphone for tone analysis, a feature that I never tried.  The device’s intelligence is all in the Halo App, in my case residing on my iPhone.

My unboxing experience wasn’t good.  The wrist band comes with a charging cradle that clips around the Halo and is supposed to mate the contacts between the two.  This is initially necessary to establish a Bluetooth connection to your phone, and subsequently to charge the Halo.  Getting this to work was much more difficult than I would have hoped.  In the end, I was able to finesse the position of the Halo so that it did connect, but it doesn’t drop into place the way that I have previously experienced with Garmin and Fitbit devices, and for a while, I was wondering if the device was faulty.

 The Halo is a light, slim wrist band with a Velcro closure.  You need to get the correct size for your wrist, but the size guide makes that easy.  I have a series 4 Apple watch that I wear all the time, so I put the Halo on my other wrist to be able to compare their usefulness.

My interest in the Halo was for its potential in the following areas.

-Sleep Tracking.

-Activity Monitoring.

-Body Fat Composition.

I wasn’t interested in its heart rate monitoring, nor the voice tone analysis.

Sleep Tracking

This was the biggest disappointment for me.  I wear my Apple Watch to bed and run a sleep app (AutoSleep) on it.  The daily results are displayed on my iPhone as you can see in the screenshot. 

Generally, the results match my recollection of how my night’s sleep went.  I do wake up briefly three or more times to go to the toilet, and I can clearly see the terrible effect that having sugar late at night has on how deeply I sleep.  In contrast, the results from the Halo bore little relation to how I actually slept, with the device repeatedly reporting that I was awake for a period of an hour or more during the night, which I most certainly wasn’t.  Based on my very limited experience I would not want to use it as a tool to try to improve my sleep hygiene.

(Editor’s note-My experience with every wearable sleep tracker I have tried (Oura, Garmin Vivosmart 4, Circul, Autosleep, Sleep++) has been similar.)

Activity Monitoring

The Halo app awards points for undertaking strenuous activities, encouraging you to accumulate at least 150 points in a week.  I was happy to receive 31 points the first day I had it on during my daily workout.  I was less happy in the evening when I checked back and found that I had only 29 points.  On investigation, I discovered that the app takes away points for being too sedentary.  The logic to this is that being sedentary for more than 8 hours is actually damaging to your health.  While this is almost certainly true, for me the punishment for something that I can’t readily alter is a disincentive.  It’s not that I don’t get up and move regularly and walk up and downstairs during the day, but most of my activities are unavoidably sedentary, which is why I do a minimum of 30 minutes of cardio every day.  For me, the Apple Watch encouragement to stand and move about as part of closing my rings is a much more positive way to have me try and improve.  I have to say that this is very much a personal feeling as to how data influences me and you may find the Halo’s model to be excellent for you.

Screen shot of Apple Watch “Move” data collected from Apple Watch

Body Fat Composition

This was one of the most interesting features that the Halo offered.  Though in fact the feature has absolutely nothing to do with the Halo wrist band and is entirely a function of the Halo app and your phone’s camera.  However, you can’t run the app without having a Halo active.

I’ve recently been involved with bodybuilding, competing in the over 70 class, so have been a gym regular who worked with professional trainers.  Weekly body fat measurements with calipers were a standard part of the regimen.  With the current pandemic raging, we haven’t been to the gym since March, so the prospect of being able to get a body fat reading at home was enticing.  The Halo app is nothing short of brilliant in how easy it is to set up and take the necessary pictures.  The software does an impressive job of creating a 3D image of one’s body as you can see.

The problem I have is with the fat percentage that it calculates. 

At 21% the app is telling me that I am close to obese.  In the past, I have had scans done at my gym with a very expensive scanner that has a platform that weighs you and rotates you around in front of a high-resolution camera to create a detailed 3D image that is precise enough to provide actual measurements of waist, chest, biceps, etc.  As you can see from the second image, there is more definition, and the number from that scan is 19.7%, so the two scans both suggest a figure around 20%. 

However, the report with the gym scan has my fat level as within the “Ideal” band rather than being on the border of obesity!  An acknowledgment that the percentages calculated from their scans are high.

Measurement using skinfold calipers (so-called “pinch” measurements) gives numbers for me between 6 and 12% depending upon the system the trainer uses.  For my age I carry a reasonable amount of muscle and I suspect that the algorithm that the Halo and the gym’s scanner uses doesn’t do well with that.  In fact, the gym’s scanner rated the owner, a very serious bodybuilder with hardly a scrap of fat on him, at around 16%.

So, the takeaway from all this is that all body fat measuring methods, with the exception of the Dexa Scan, yield figures which can be used as a guide to changes in fat percentage but don’t provide an accurate absolute number.   Considering the Halo scan, my feeling is that it would be useful as a motivator if you were considerably overweight and were targeting a substantial fat reduction say from 40 to 30 percent.  The changes would be very apparent, and you would have an excellent before, during, and after record of your progress.  For me the scan is interesting, but I am fairly happy with my current body composition and will concentrate on maintaining or possibly increasing my muscle mass, coupled with watching my weight and looking in the mirror! Any small changes in my fat percentage would I suspect be hidden in the variability caused by how you stand or hold yourself during the taking of the four photographs that the Halo software uses to build the image, so repeated scans wouldn’t offer me much information.  


For Sleep Tracking and Activity Monitoring, the Halo didn’t live up to my hopes.  The Body Composition scan may be an alternative to paying for a scan at a gym if the limited information it gives you will help you achieve your composition goal.

I must stress that I spent only a few days with the device and did not explore all of its capabilities, so I am sure I have underestimated its total capabilities.  Also bear in mind that the functionality is in the software interpreting the data provided by the wrist band and that software is in its first iteration and will probably get more capable over time.

I have returned the Halo to Amazon.



Accurate Body Fat Assessment

In my post on body fat measurement I describe the various tools I have evaluated to assess body fat including BMI, waist circumference, skin fold calipers, and bioimpedance.

Bioimpedance testing on the Qardiobase scale told me I was made up of 24% fat placing me perilously close to “overfat” for males over 60 years of age.

The various commonly available modalities for assessing body fat, visceral fat, and obesity placed me somewhere between normal to bordering on obese but I suspected there were inaccurate.

After analyzing the literature on the topic I decided that DEXA assessment was the gold standard for fat measurement and I believe I now have a convenient, inexpensive, and highly accurate tool that will provide precise estimates of my patient’s visceral body fat.

I searched for high-quality DEXA scan locations in the St. Louis region and found that Logan College of Chiropractic had a state of the art scanner and was offering body scans for $15. That is not a typo.

The scan took about 10 minutes and uses extremely low x-ray dosing. No IVs, no contrast, clothes kept on.

My final percent body fat turned out to be 11.9%, about half of what other modalities were telling me. That percentage puts me in the blue underfat portion of the chart for my age and would be healthy for an 18-year-old.

I feel that for many of my patients a precise measurement of body fat will allow us to successfully identify and treat cardiometabolic disease. High body fat numbers will help provide motivation for the “skinny fat” individuals to make the lifestyle changes needed to make them metabolically healthy.

Unfortunately, the Halo and most body fat assessments easily available to the public are unreliable, unproven, and will be misleading.

Adiposigraphically Yours,


N.B. Online the Halo is being compared to the Whoop band, a device which I was previously unaware of . One website notes that the Whoop subscription starts at $30 per month:

The Whoop Strap 3.0 has a different type of philosophy and selling point. This company is not really selling the fitness band but instead it is selling their membership. Therefore, it is more comparable to the Amazon Halo than other fitness trackers. In fact, the CEO of Whoop accused Amazon of copying their product.

If there are any Whoop devotees at there please let us know what makes membership worth $360 per year.

Also feel free to share any Halo observations with me.


2 thoughts on “Can The Amazon Halo Wrist Band Provide Useful Information on Body Fat and Sleep Quality?”

  1. I have been using the FitBit Charge 4 with overall very satisfactory results over the last 6 weeks.

    Enrolling in their subscription program is essential to unlock the maximum benefit.

    The FBCF has a new concept called Active Zone Minutes, which measures my daily physical exertion, in what I describe as Farm Boy Exercise. Briefly, it tracks your rate and assumes HR elevation is due to exercise. Mildly elevated heart rate earns Active Zone Minutes one for one, whilst moderately elevated heart rates earn Active Zone Minutes two for one.

    The WHO recommends 150 minutes a week of moderate exercise, while the FBCF logs my FBE AZM as often exceeding 160 minutes a day. I am very active, often building a sweat that lasts for hours. However steps walked is disappointingly low, and not a good metric for my exercise.

    The FBCF automatically calculates the HR zones based on age and resting heart rate.

    The sleep feature of the FBCF has been helpful in improving all aspects of sleep – the iPhone app gives a comprehensive reports. This feedback has helped improve my sleep hygiene. Plus 0.5 to 1 mg of prescription grade Melatonin.

    As one who is often woken by chronic pain, identifying factors that exacerbate the nocturnal pain is a definite plus for the FBCF. Summing up, better sleep is resulting.

    Like most of its ilk, it is not without its foibles, but overall I value its contribution to my health.

    I am looking forward to your review of the Withings Scan Watch with ECG and sleep monitoring. At the moment I am searching for a jeweller who can replace the battery in my Kardia Apple Watch Smart Band. I still use the original two pad gizmo, and value the peace of mind it provides.

    I have upgraded my Omron BP to the Intellisense monitor, and have found its arrhythmia detection to be very accurate.

    • Chris,
      The FBCF sounds like a good for for you. I’m curious how it determines the Active Zones for your heart rate response. If it is calculating a predicted maximum HR for you based on your age how does it determine the points per HR response? What aspects of the sleep feature are helpful?


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