new Watch App for Lumen on Apple

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Lumen releases its first app for Apple watchOS

The latest update to the Lumen app on iOS also heralded the arrival of their first partner app for the Apple Watch.

The app is an information-packed recap of your latest fat-burning readings plus your planned diet for each meal of the day. Even more useful will be the carb logger that lets you log your actual carb consumption for each meal.

What is Lumen?

Recommended: Detailed Lumen Review

Lumen is a handheld sensor that you blow into. It measures the difference in carbon dioxide from the breath you inhale to the breath you exhale. In many circumstances, this can be equated to the degree to which you are burning fat/carbs as the fuel source for your body.


Athletes and dieters both want to be good at burning fat albeit for different reasons. Lumen helps with that.

Using its understanding of your 24×7 breath signature, Lumen then OPTIONALLY recommends a keto style diet to sensibly guide you toward metabolic flexibility ie the ability to more easily switch between fat and carbs as a fuel source.

That’s it in a nutshell and if you want to read MUCH more detail I wrote a detailed review of Lumen in early 2021 and I’ve used it myself since then, mostly for athletic purposes. I liked Lumen’s Garmin CIQ widget but didn’t really use that so much.

How to get the new app for your Apple Watch

You already have the Lumen app installed on your phone. First up go to Apple’s app store and quickly check there’s not a new version. You’ll need version 2.4.773 or newer.

Simply updating your phone app might be enough to also sync the new watch app to your watch. If not go to Apple’s generic WATCH app on your iPhone and scroll down on the first page through a list of all the apps. That list should have Lumen in it and you need to click it to check you’ve allowed it to be synced to your Apple Watch.

That’s it.



What does the new Lumen app do on the Apple Watch?

The watch app does NOT replace your smartphone app which you will still need to take and tag readings throughout the day. You will also need to plan & sync your workouts on the smartphone app so that Lumen can account for those in its daily recommendation of your carb intake.

So the watch app suggests your macros for each meal and gives you details of all your tagged readings and fat-burning state. There’s also a carb logger

Carb Logger

Once your diet is planned it should automatically sync across to the watch.

For each meal, you are recommended the number of servings (and grams) of your macros and you can simply log the number of carbs for the meal. I’ve not used this yet as it isn’t on my version of the app but I probably will start to as soon as it’s available. Previously, you had to input your carbs in total for the previous day on the smartphone and I just guesstimated that. Now I should be able to be more accurate and more easily able to do it via the watch.

Meal Plan

Your meal plan is synced to the watch after your early morning reading and you even get to have a snack 😉

Fat Burning State

The readings taken on your smartphone are synced to the watch and you can quickly check them along with which events of your day they were tagged against.

This is nice info but a bit of a #shrug as you will already have seen it on your iPhone. It’s the carb logger that will be far more useful.

What Next?

The app has been released but not formally announced and I think these features are a tad buggy right now. There’s also the ability to take HR readings on the iPhone app that I hadn’t noticed before which doesn’t work. So download it now for a quick play but perhaps hold off for a couple of weeks for it all to work smoothly.

Looking ahead at what new features might later be added, I suspect that the Apple Watch app will be brought in line with the existing Garmin widget in the sense that you might get an extra info screen added to show your current metabolic flexibility as well as sync the body battery information equivalent that is already on the Apple Watch (SDNN).

Slightly further down the line, I would hope that Lumen can estimate future workouts from your workout history or read workouts specifically from a workout plan. Currently, the iOS app accommodates a repeated one week schedule of your workouts and provides a carb boost to fuel them.

Recommended: Detailed Lumen Review


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