This blog post is sponsored by Lumen. However, all views are my own, and Lumen has had no say in the content you’re about to read.

For the last few weeks, I’ve been blowing into a small device that’s connected to my iPhone via Bluetooth in order to measure my metabolism.

Now, there’s a collection of words I never thought I’d form into a sentence.

Lumen is pitched as “the first device to hack your metabolism”. It promises to help users become more metabolically flexible and, in turn, have an easier time losing weight, keeping it off, gaining better sleep, and finding more energy to play with each day.

Sound too good to be true? Let’s find out!

What is Lumen and how much does it cost?

Lumen comprises a hand-held, portable metabolic measurement device and an app for your smartphone (it’s compatible with both iOS and Android).

The Lumen device is small enough to fit into most pockets and comes with a handy little travel case to keep it safe. Battery life is rated at 14 days and although the device is topped up via a charging base, those two weeks of juice should mean you can leave the base at home while travelling.

It includes a golden CO2 sensor which is tasked with measuring your metabolism and a satisfyingly magnetised lid to hide the part into which you blow during measurements. The Lumen device is well-made, easy to use, and fairly innocuous. Indeed, when you consider that this type of measurement was previously only available via much larger devices within professional healthcare settings, it’s impressive stuff.

You can try Lumen risk-free for 30 days and gain a full refund within that time if it’s not for you. If you do decide to proceed, there are three ‘tracks’ to choose from, each of which includes the Lumen device at no extra cost. The Metabolism Booster track is the cheapest at £249 for six months (£25 per month thereafter) and is aimed at people who “want to learn about their metabolism, lose weight and shift to fat burn”. The Advanced Fat Burn track is a 12-month program for £299 (that’s the current sale price) and promises “enhanced” metabolism. Lumen VIP is the top-tier track which is currently available on a Black Friday deal for £349 and offers 12 months of personalised support and direct access to Lumen’s team of metabolic experts.

So, it isn’t what you’d call cheap, and if you’re already paying for a gym subscription, it’s yet another monthly fee to account for. But what if that gym membership isn’t delivering value? Is Lumen a worthy companion or substitute?

How does Lumen work?

The premise behind Lumen is actually pretty straightforward, although I admit it took me a while to get my head around its ultimate purpose.

Lumen Review

Each day, you’re encouraged to measure your metabolism via the Lumen device. There are prompts for doing so via iOS notifications at the start and end of the day, but you can do it whenever you wish. Exercise, eating, and fasting are all recommended measurement opportunities in the Lumen app, and the more you measure your metabolism, the more data you feed Lumen for the most appropriate feedback and advice.

Lumen review

Measuring is undertaken by exhaling, holding your breath, and then breathing out, all while holding the Lumen device to your mouth. The device measures the amount of CO2 you’re exhaling. If the CO2 level is high, you’re burning carbs, and if it’s low, you’re in a state of fat burn. A Lumen Level score is then issued by the app, which ranges between 1 to 5.

Score a 1, and your body is burning fat for energy. Hit a 5, and you’re burning carbs for energy. Lumen also connects to Apple Health to keep an eye on any workouts you perform each day, thus building the data from those exertions into your daily summary. It’ll also track your sleep cycle (to account for overnight fasting) and you can input your food intake manually to give the app as much data to go on as possible.

Lumen takes that data and offers daily guidance on what to eat and the types of activities you can undertake to ensure your body consistently burns more fat than carbs (which, in turn, leads to weight loss). These activities range from reducing screen time to undertaking specific exercises, eating certain types of food, and reducing your caffeine intake.

The idea is that Lumen helps guide your body to a point of burning fat (rather than keeping it stored) that’s sufficient to lose and maintain a healthy weight and only burn carbs when you need to. That’s where the daily goal setting and guidance offered by the app are designed to remove the need to fully understand the science for mere mortals like you and me.

My experience

The measurement process is super straightforward, even if it took me a couple of attempts to get the breathing right. Via onscreen prompts on the Lumen app, you’re instructed to breathe into the Lumen device deeply for a few seconds, hold your breath for ten seconds, and then breathe back out into the device.

The Lumen app is nicely designed and, crucially, approachable. I’ve often found health apps to be impenetrable in places, but the Lumen team has done an impressive job in making the data and guidance super easy to follow and understand.

Lumen review

The ‘Today’ tab tells you immediately what type of carb day you should be aiming for (at the time of writing, mine is a “medium” carb day), your nutrition plan (split between net carbs, fat, and protein), and then your daily goals. You can also access your food log, and review a bunch of meal suggestions via recipes and food lists.

Lumen review

Lumen hasn’t felt like a chore thus far. The measuring process takes around a minute to complete (when you factor in the breathing and goal setting) and the Lumen device is convenient enough to carry everywhere.

It’s worth noting that, being a relatively simple guy when it comes to the way in which I manage my diet and fitness, and despite the aforementioned approachability, it has taken me a while to get my head around how Lumen’s coaching style can benefit me.

After a few weeks of use, I’d consider myself a light user. I’m barely skimming the surface of what Lumen can do, but as someone who’s comfortable with his weight yet slightly curious about the effectiveness of his diet, the simple process of measuring my metabolism two or three times a day and paying attention to the nutritional guidance has been enlightening.

I haven’t really modified my diet or exercise routine since using Lumen. Instead, it’s been comforting to know that I appear to be burning fat when I should be and ingesting the right amount of carbs when my body needs it. The benefit Lumen has offered is in highlighting when I perhaps shouldn’t eat that carbohydrate-drenched lunch, or when a rest day is called for in order to give my body a chance to recover and increase its carbohydrate store.

This leads me to an inevitable conclusion about Lumen.

Conclusion: is it worth it?

Lumen is worth it, but it’s important to establish who this device is for.

It’s not me. This is for two reasons. Firstly, I’m relatively happy with my weight and fitness levels; I’m the healthiest I’ve been in that regard and feel like I have good control over those elements of my life.

Lumen Review

One area in which Lumen can clearly help me is focusing on eating and sleeping better – that goes some way to make it a tempting proposition, but I’d personally struggle to justify the additional cost over a gym membership that I use comprehensively.

However, judging Lumen on my use case alone isn’t entirely fair. Lumen can do so much more for the right type of user. It’s for the person who really wants to understand what’s happening with their metabolism and why they’re struggling to either lose weight or maintain weight loss. It’s also for the sort of person who finds logging food intake and digging into the numbers behind their body interesting. Again, that isn’t me – I’m too lazy to make that form of logging and analysis a habit.

This isn’t a bad reflection of Lumen at all – it says far more about me. There are reasons devices like this exist, and I think Lumen has hit its target market perfectly. The measurement process is – regardless of my own misgivings – addictive, and the Lumen device itself is a great companion to carry around with you.

The app works as a brilliant goal tracker, too. The fact that it prompts you with goals based on your metabolism measurements removes the guesswork from setting your own goals and enables you to focus on what matters for your body each day. It’s also a brilliant food tracker in its own right, and can probably replace any other app you’re using for that task.

I’ve enjoyed my Lumen experiment and can see exactly why it would benefit some users. It’s not cheap, but when you consider what we’ll happily pay for gym memberships that are often left to gather dust, it’s not a bad way to invest in your health at all.

Find out more about Lumen here (enter code ELLIS at checkout for $50 off)