During COVID, I gained some weight and my HbA1C was pre-diabetic level. In 2023, I started to exercise more to lose weight. I purchased Garmin fitness watch to track my exercise and also to motivate me. Well, the more I exercised, the more I ate. And I was actually gaining weight.
Then in November 2023, I had a wake-up call when I got my blood test showing that I was diabetic. That was when I also focused on food intake. And I was able to lose 25 lbs in 2.5 months.
I went thru multiple Garmin models, because I had problem with some of the features. In hindsight, it seems that my weight and associated health issues affected the Garmin metrics.
Fitness Watch
I'm not new to smartwatch or fitness watch. I have owned 2 Apple Watches previously (AW series 3 and AW series 5 stainless steel). Then after I switched from Apple iPhone to Samsung Galaxy android phone, I can no longer use AW. So I got Fitbit Charge 4. But Fitbit is piece of shit, so I stopped using it. Last year, I did take it out of the drawer and started using it again. But Fitbit is just so bad and so frustrating to use. I started to shop for Garmin watch.
I went through 3 Garmin watches, because I multiple issue with the features:
Garmin Forerunner 245 (with Elevate Gen 3 sensor)
Garmin Forerunner 255 (with Elevate Gen 4 sensor)
Vivoactive 4 (with Elevate Gen 3 sensor)
The HR and GPS all worked well on these models. But I had major issue with sleep tracking and body battery. I purchased FR 245 first. I thought issue was due to older Gen 3 sensor. So I return FR 245 and got FR 255, which at the time had the latest Gen 4 sensor. FR 255 was actually worse than FR 245 in sleep tracking. I returned both Forerunner units. And I ended up getting Vivoactive 4. Not because Vivoactive 4 was any better; it had the same sensor as FR 245. Just that Vivoactive 4 was discounted and much cheaper.
Weight Gain & Loss
From January thru October 2023, I ramped up my exercise. As I exercised more, I continued to gain weight, because I ate more as I exercised. So although Garmin watch helped me to track activities, it was not helpful to help me lose weight. Obviously, this is tongue-in-cheek. Fitness watch does not equal weight loss.
In November 2023, I got my blood test result that I was diabetic. I then went Keto + OMAD (one meal a day) + CICO (calorie in calorie out) + continued exercise. I was able to lose 25 lbs in 2.5 months. Garmin is instrumental in helping me count activity calories: the CO part of CICO. This is link to my post on the details of my weight loss: https://jimmy1photo.wixsite.com/blog/post/keto-omad-cico.
Below is my weight history for past 9 months, when I started tracking. My weight hit highest point at beginning of November 2023. Then I started my Keto + OMAD + CICO in December. And can see the downward trajectory on weight.
Obviously, it required a change in attitude, habit, and commitment to make a change in diet to lose weight. The fitness watch is a tool. And during my weight loss, I was able to see how Garmin metrics were affected by my health and weight loss.
Weight Loss Impact on Garmin Metrics
First, there were couple metrics that I thought were marketing fluff: Sleep Tracking and Body Battery. I will discuss issues I encountered and how the data looks before and during weight loss.
Then I will show data on Heart Rate, Pulse Ox, VO2 Max, and Stress. These metrics all improved with weight loss.
Sleep Tracking Issue
I typically do not sleep much; typically around 7 hours each night. I rather be watching tv/movie, gaming, or read, instead of sleep. Also, I'm likely light sleeper. I typically have to get up to use the bathroom once.
I didn't have any problem previously using Fitbit Charge 4 for sleep tracking. Fitbit is uncomfortable, had crappy display that is not usable in bright outdoor light, and had insensitive touch screen. But those bad features didn't affect sleep tracking.
When I got Garmin, it was really inaccurate at sleep tracking. I would sleep around 7 hours, and Garmin will report I slept < 6 hours. Some days, even less, down to 3-5 hours. Ridiculously bad.
It seems most Garmin users do have this issue. But I cannot explain why I had so much problem. And I had the problem with 3 different Garmin watches: Forerunner 245, Forerunner 255, and Vivoactive 4. It was not model dependent. FR 245 and Vivoactive 4 have older Elevate Gen 3 sensor; FR 255 have newer Elevate Gen 4 sensor. So it was not sensor dependent either. Actually, FR 255 with Gen 4 sensor was worse, in that it tend to measure the lower sleep duration. I suspect that Gen 4 sensor is more sensitive and pick up my movements during sleep, thinking I'm awake.
Body Battery Issue
Due to the low sleep duration tracked by Garmin, the Body Battery metric was also screwed up. My body battery didn't charge up much during sleep overnight. And during the day, my body battery will be drained before noon. This was not related to how I felt or my exercises.
I thought both of these metrics are just marketing features that really do not work. And I stopped using Garmin during sleep.
Before and After Weight Loss
Sleep Duration
I cannot explain Sleep tracking and Body Battery data. Just that after weight loss, these metrics looks better, more realistic, and more representative on how I felt and my activities.
For sleep, I assume it is because I now sleep better and more like average person. Graph below is my sleep duration in September 2023. I rarely met the duration that Garmin's target duration (in green); only 5 out of 28 nights. There was one night where Garmin only tracked 3 hours of sleep; and many nights < 6 hours of sleep. I knew I slept more than that, but it was likely poor sleep.
After losing 20 lbs, I noticed I have been sleeping better, and also a bit longer. So couple weeks ago, on February 5th, I started to use Garmin Vivoactive 4 again to track my sleep. And I was surprised the Garmin tracked my sleep much better now. It now measures 6-9 hours per night, which is closer to my actual sleep duration. And 5 out of 12 nights, I met Garmin's target duration (in green).
Body Battery
As for Body Battery, the data is also more usable now. Below is my Body Battery data from September 2023. My daily max ranged 25 to 75. The lows often hit 5 (which is basically zero, because Garmin limits 5 as lowest possible number). More importantly, the Body Battery metric was nothing close to how I felt or based on my activities.
Below is my Body Battery numbers since January 2024. From January to February 4th, I didn't use Garmin watch for Sleep Tracking. So looks like Garmin just estimates recovery without actual sleep data. So it likely uses rest vs activity. OK, not sure how to use that info.
From February 5th, I restarted using Vivoactive 4 for track sleep again. Body Battery numbers actually went down with actual sleep data. Still, Body Battery numbers now make more sense and is more realistic, compared to September 2023 above. My daily max rangs from 70 to 100. And my lows are also reasonable around 25 to 40. The days when I had low Body Battery actually matches with strength and cardio work out. And I no longer run out of Body Battery by noon.
Heart Rate
As I lost weight, I noticed changes to my heart rate:
Resting heart rate dropped. See data below.
Max HR during exercise increased. Previously, my max HR is around 120-130 bpm during elliptical exercise. Now, it goes up to 150 bpm in same exercise. It is possible that I'm lighter and fitter now, so I go faster, and thus the max HR goes up. Hard to say. I will also share some Max HR data below.
Typical HR during exercise dropped. Previously, during light exercise and walking, I was around 90-100. Now, my HR is < 90. And I have difficulty getting into lowest HR zone. I don't have data to show this, but this is quite apparent during exercises.
Below is my Resting HR from September 2023 in 1st graph; and from last 4 weeks in 2nd graph. Firstly, the average of the daily Resting HR in September 2023 is 54.5 bpm; average in past 4 weeks is 54 bpm. Although it is not much of a delta, it has dropped. Also, in the second graph, I can see decreasing trend during my weight loss.
Below is the Max Heart Rate measured by Garmin. Back in June 2023, it was around 169 bpm. Then in October 2023, near my heaviest weight, it was 152 bpm. Now, in February 2024, it is back up to 165 bpm. The trend is obvious, but this data can be misleading. I believe this Max HR depends on the type of exercise. And I do both outdoors and indoors activities. During summer, I tend to do more outdoors activity. And in winter, I switch to more indoor. So when activities differ, the Max HR can vary.
Pulse Ox
Below is Pulse Ox reading from September 2023. My lows are typically 91%.
Below is Pulse Ox in past 4 weeks. Lows are at 94%, except for 1 outlier at 92%.
VO2 Max
My VO2 Max was 38 ml/kg/min in June 2023. Then it slowly dropped to lowest point of 35 ml/kg/min in November 2023. Now, in February 2024, it has increased to 41 ml/kg/min.
I'm not training for competition race, so I don't pay attention to VO2 Max. Not sure how significant is delta of 6 ml/kg/min. Percentage-wise, it is 17% increase, which seems quite significant. But in term of numerical value, 6 does not seem like much. In any case, it is going in the right direction.
Stress
Stress is something I do not know how to interpret. Because I don't find Garmin's Stress metric during the day to match my exposure to stress. When I'm at work with real life stress, Garmin's Stress metric is low. When I'm at home watching TV, metric is high.
Regardless of the interpretation, it is quite surprising to see the shift in stress, that coincides with diet and weight loss. See graph below. I started Keto on December 1st; OMAD soon after. And there is a clear drop in Stress value from December.
I believe Stress is interpreted from HRV (heart rate variability). My Vivoactive 4 has capability measure HRV, but it will not report HRV data. So I assume my HRV has gone up. This is how Garmin disables features to segment the product tiers and prices.
Conclusion
I previous thought that Garmin's metrics were kind of gimmicky. Sure, the metrics give users goals to strive for; and keep users motivated. But I doubted their accuracy and effectiveness. Because I don't train for competitive racing, I don't really use some of these metrics, and I doubted if they represented real life performance.
I am surprised to see the improvement in my metrics as I lost weight in the past 2.5 months. Although I don't know how to interpret some of these numbers, it is great to see that they are going in the right direction. And these metrics reinforces that my weight loss has big impact on my health.