The question I get more than any other isn't about protein or lifting. It's some version of this: which tracker should I actually buy?

I've worn an Oura ring since 2022. These days I also rotate a Whoop, a Hume Band, Fitbit and an Elonga, sometimes all at once, which my husband finds a little ridiculous. All part of the wearable tester life though, so we both put up with it. So all that is to say, I definitely have opinions on which is best for what, and I have a bit of data.

Before I tell you which one I'd hand my sisters (hey Sheila and Erica!), here's the part marketing leaves out. Your wearable is very good at some things and mostly guessing at others.

What they get right

The strongest thing these devices do is heart rate. A 2024 umbrella review in Sports Medicine pooled hundreds of validation studies and put the average heart rate error at about 3 percent. Resting heart rate, heart rate variability trends, breathing rate, these are fairly accurate on most devices. This is where the technology earns its keep and it can be useful for catching when you're run down or fighting something off before you feel it.

What they mostly guess at

Sleep staging is the soft spot. That chart splitting your night into light, deep and REM is an estimate built from movement and heart rate, not a reading of your brain. The same review found trackers tend to overshoot total sleep time by more than 10 percent on average.

Calorie burn is even shakier. That review found energy expenditure estimates can range anywhere from about 20 percent under to 15 percent over the real number. So treat the calories out figure as a loose ballpark, not a budget to try to eat back. I personally never look at this number, since machines and wearables are notoriously off on calorie counts.

To be fair to Oura specifically, it holds up better than most for sleep data. A 2024 validation study in Sleep Medicine tested the Gen3 ring against overnight lab sleep studies in 96 generally healthy adults and found good agreement for total sleep time and for time in light and deep sleep, with sleep and wake called correctly about 92 percent of the time. It did undercount REM by a few minutes. Not bad for something that lives on your finger.

One catch worth knowing. Those are group averages. A 2025 study in Scientific Reports that put rings up against lab sleep studies found the averages can look great while any single night is off by quite a lot. So trust the weekly trend, not last night's exact deep sleep number.

So which one?

Here's my honest side by side, having worn so many of these devices. I have a full review of all of the ones below at the website.

Oura is the one I've worn longest and the one I'd hand a friend who wants the best sleep and recovery data in something that's easy to wear. It's a ring, so it's the easiest to wear daily. The trade is a monthly membership on top of the ring price. Take a look here.

Whoop is the one that's best for when I'm training hard and want strain and recovery data. No screen, subscription based, it's built for athletes and people who like a deep dive into data. If you want a single number telling you whether to push today or back off, this is it. That said, I think the Fitbit does almost the same job and it's a lot cheaper, no subscription. Whoop is here and Fitbit here.

Hume Band is the one I like most for the longevity and metabolic angle. I've worn it across versions, going back to the original and I'm on the 2.0 now. I like the form factor and the price is friendlier than a ring plus a membership. Hume Band is here and best for people who want to focus most on overall health and longevity.

Elonga is the odd one out, in the best way. It isn't an all day tracker at all. You strap it to your forearm for three minutes each morning while you're still lying in bed, then set it aside. In those three minutes it reads your heart rate variability and unlike most trackers that only capture the recovery side, it separates stress from recovery so you see both. On one rough day it showed my stress up 78 percent while my recovery dropped 10 percent, the kind of detail my ring and strap only hinted at with a slightly higher resting heart rate. It runs about $99 a year with the band included and no big upfront device cost. If you already wear a ring or watch and want a deeper read on your nervous system without living in a device, this is the one I'd add. If what you want is just step counts and workout tracking, skip it. Elonga is here (use code healnourishgrow for 10 percent off).

My one rule for all of them. A tracker is only worth the money if it changes what you do. If the data mostly just makes you anxious, the best wearable is no wearable.

Hit reply and tell me which tracker you're wearing right now, if any, and whether you actually trust it. I read every response and I write back.

Have a great weekend!

P.S. If you're on my meal plan list, the August High Protein Kitchen plan landed in your inbox Wednesday...and if you're not yet, you can grab it here: August High Protein Kitchen​​​

P.P.S. Before you spend a nickel on a gadget, the highest return tool I have is free. My protein calculator takes about 30 seconds and gives you the one number that matters most for holding onto muscle as we age. It's here.