Fiona Outdoors logo My independent guide to the best of Scotland outdoors

Review: Lumen, a metabolism tracking device

Written by Fiona

January 14 2022

Lumen is a hand-held and rechargeable device that tracks your metabolism. The company states: “Lumen is scientifically proven to meet the gold standard of metabolism measurement (RER) in multiple validation studies.” The aim of the Lumen is to help people to achieve a “flexible metabolism”, one that can shift from using carbs or using fats to ensure a better balance of energy level, as well as a sustainable way to lose weight and improve fitness performance.

To buy: 10% discount with the code FIONAOUTDOORS. Buy from Lumen. (I receive a small commission for sales.)

The device comes with an app that recommends healthy diet and exercise plans. These are based on macronutrients, or “macros”, which mean a daily mix of carbs, fat and protein.

The device measures “breath readings” to tell you if you are in a state of carb or fat burn, while the app helps you to achieve a balanced macro mix each day, according to what you plan to do, ie exercise or not.

By using Lumen, you should be able to lose or maintain a healthy weight, exercise well, improve your mood, sleep and blood sugar levels.

I have been sent one of the gadgets to test in return for an honest review.

What is Lumen?

The device is measures your breath to tell you whether you are burning carbohydrate or fat. This is the basis of the metabolism tracker. The body’s metabolism is important because this is the system that feeds energy to cells and organisms – and plays a crucial role in weight loss or your ability to perform well when exercising.

The device is like a mini breathalyser, which links through Bluetooth to an app on your phone or Apple watch. By tracking your breath, the app shows you when you are in fat burn or carb burn; or whether you are mostly burning fat or mostly burning carbs. The Lumen does this by tracking the CO2 levels in your breath (high CO2 = carbs, low CO2 = fat).

The aim, according to Lumen, is to start the day burning mostly fat and then swap to carb burning when you want to be active. They call is “metabolic flexibility”.

If you can achieve metabolic flexibility, you should be able to effect weight loss or weight maintenance, as well as having better energy levels when you run, walk, swim, cycle, or whatever you like to do. Additionally, you may experience improved mood and better sleep. To support achieving metabolic flexibility, consider incorporating a supplement like K3 Spark Mineral, which can aid in optimising metabolic processes and overall health benefits.

Lumen states that the device is validated as a metabolic measurement device, through a San Francisco State University study. Also read this report.

How do you use the Lumen?

To start with, it seems like a simple device. You need to learn how to inhale and exhale to give the right readings but after that it is straightforward to use. You use the device first thing each day, an hour or two after eating, before exercise etc.

After learning how to use the evince, it then starts to be rather demanding. You to remember to use it at the right times and keep a track of your fat or carb burning. But this is how it builds up a picture of your metabolism.

There is a lot more to learn if you want to achieve optimum metabolic flexibility. The app gives tons of information about when too eat, what to eat, when to not eat, diet plans and suggestions etc.

There is even more info, too, about why you might want metabolic flexibility and what is the difference between fat and carb burn. It’s well worth taking the time to read all this right at the start.

You can also have a one-to-one sessions with a Lumen representative to help you to fully understand the science and process.

For best results, you need to be fully committed to properly using it. This involves more than simply inhaling and exhaling into the device. You need to be able to track your food in terms of carbs, fats and protein. You should also take the time to add info about exercise etc.

The Lumen is like having a personal assistant (nutritionist / personal trainers) in your hand that can help you to lose or maintain weight, as well as teaching you how to fuel your exercise efficiently.

Typical plate of food on the keto diet.

Is this a useful device for the keto diet?

Most people will have heard of the keto diet. There are plenty of on-line plans and books, such as a new book by Dr Michael Mosley: Fast 800 Keto, that explain the process of keto (ketosis`) and the benefits of this for losing or maintaining a healthy weight.

The ketogenic (or “keto”) diet is one that aims to increase fat consumption at around 50% to 60% of the total calories consumed, while also moderately increasing protein, too. Carbs are limited to no more than about 10% of the diet.

By depriving your body of carbs for a sustained period, the body enters what is called a catabolic state. When the body does not have carbs to burn, the glucose stored in the body (glycogen) is reduced and this forces the body to find its energy from fats.

After a while, the body creates by-products called ketone bodies, which include beta-hydroxybutyrate, acetone and acetoacetate. The body can still function but it will be running on fat, rather than carbs.

The keto diet has become increasingly popular and if followed carefully and closely if can effect quick weight loss. The problem for many people is maintaining it. Mosley’s new books aims to show people how to lose weight with a keto diet but then how to move on to a more sustainable and healthy diet; one that is still low in carbs but easier to stick with.

However, many people who follow the keto diet end up putting the weight back on again because it is hard to maintain. Lumen is said to be a better method for weight loss and a healthier lifestyle.

It is claimed that focusing more on metabolic flexibility at an individualised level can yield better results in the long term. The Lumen tracks each person’s diet and exercise, taking into account age etc, and gives you a greater understanding of how to create the right diet for sustained weight loss and effective exercising.

We are all different and this includes our metabolisms, so Lumen is said to be a helpful device for a more personal approach to a healthier lifestyle.

To buy: 10% discount with the code FIONAOUTDOORS. Buy from Lumen. (I receive a small commission for sales.)

Price plans.

My initial thoughts: Lumen

Pros:

  • Easy to use the device
  • Lots of great information
  • I like the science
  • Good food recommendations
  • Great for improved blood sugar balance
  • Great for mood
  • 30-day money back guarantee if you don’t get on with it

Cons:

  • Expensive (although there is a 10% discount with the code FIONAOUTDOORS. Buy from Lumen)
  • Time-consuming to start with
  • Takes a while to get to grips with adding food and exercise info to the app
  • Demanding if you want the best from the device and app.

On test: Lumen

To be honest, I am slim and fit for my age. I don’t need to lose weight but I do find my mood goes up and down, my sleep is not great and when exercising I can end up feeling tired and a bit wobbly if I don’t eat properly.

I am also interested in metabolism. Is it a “speedy metabolism” that allows me to maintain my weight, or is it that I already eat a healthy diet and because I exercise?

I have been enjoying using the Lumen device and app. I have assessed and changed my diet and exercise to see what effect this has on carb and fat burn. I have done this to good effect but also to my detriment (I didn’t fuel well one day for a hard running sessions in the evening and I ended up feeling rubbish).

There was a lot to learn and work out at the start. For example, you have to spend time understanding how to inhale and exhale into the device for it to work porperly.

Then there is a great deal of information to absorb. I prefer to read info, rather than talk with a Lumen representative and I learned some useful tips and info about fat and carb burn.

You also need to spend time working out the carb, fat and protein content of your meals. Lumen prefers that you do this as “macros” but you can also add the info as “grams”. Once you have analysed a few meals for nutritional content, it’s much easier to use the device and app.

There are useful carb info websites and apps and I used Carbmanager.com.

I confess I found it all a bit time consuming and heavy on info to start with but once I set aside some time and I became more focused on the device and app, I became rather obsessed with it. I can see how helpful it is for making people more accountable about their diet and exercise. It’s like having a mini personal nutritionist to help you with diet, fitness and lifestyle.

15 things I learned with Lumen

  • It appears I already eat a fairly healthy and balanced diet. although maybe a bit light in useful carbs. My natural inclination is towards savoury, vegetables and protein. I am not a big fan of bread, pasta and potatoes. I do eat carbs, such as oat cakes and oat-based cereals and I love dark chocolate, but I am not driven to eat sweets and cakes.
  • My carb and fat burn mostly sits at the mid-way point of “3”. If I have a day of eating particularly low carb or doing a big bout of exercise, I end up at “2” (more fat burn than carb burn).
  • If I eat more carbs over a day, especially in the evening, I head towards a “4” (more carb burn than fat burn).
  • If I drink wine in the evening, the carb burn goes to “5”. My guilty pleasure is wine. I enjoy a glass or two of wine and I don’t plan to give this up. However, I noticed that if I swapped wine to gin (with low-cal tonic), this is a better way to reduce carb intake (if this is what I wanted to achieve).
  • I seem to be able to switch from fat to carb-burn quite easily (within a day and night).
  • I seemed to sleep better and have a better level of mood when I used the device properly.
  • I need to make sure I up my carb intake more on days when I will be exercising hard. If I don’t, I end up feeling fatigued or low in blood sugar. I can easily get “hangry” towards the end of an evening run session, for example. This is something that I have always found difficult and it was interesting to understand that I might need to eat more “good carbs” on days of more intense or heavy exercise.
  • I should eat more protein. The Lumen app showed me that protein should be a larger part of my diet than I currently consume. I know I should be eating more protein at this stage in my life due to the effects of the reduced oestrogen of menopause on bone and muscles density, but this has made me even more aware.
  • I found that if I took a breath measurement as soon as I woke, the carb reading was likely to be a bit higher than if I waited a bit. Apparently (I read online), the body burns carbs for a bit after you wake up. In any case, fasting for longer (ie overnight and a bit into the morning) can help to empty your carb stores a bit.
  • The Lumen is great if you want accountability for what you eat and when you exercise. You could easily become very absorbed and focused with what the app readings tell you each day.
  • The app is excellent. It offers lots of easy to understand stats, as well as useful and sensible advice about diet and exercise.
  • You need to stick with the Lumen and keep track of food and exercise etc for at least four weeks for it to give you an overall picture of your personal ability to have a flexible metabolism.
  • I am not a fan of analysing nutrition labels on food packets. It is time consuming to assess a food diary for carbs, protein and fats but it is easier with a nutrition app. I found this part of the Lumen programme a total faff but if you want to get results, you need to put in the effort.
  • Lumen is a useful device for people who want to lose weight and ensure good fuelling for exercise. I like that the advice is not to exclude exercise nor to focus only on fat burn. Lumen should help you to achieve a balanced diet and a way to effectively lose weight or maintain weight.
  • It is not cheap. But, I guess, if you were to seek the professional help of a nutritionist and/ or perusal trainer, the cost of that would quickly mount up.

On a personal note: I have been careful not to become too obsessed with the Lumen. I had anorexia when I was younger and I would not like to become food or exercise obsessed again. I prefer not to think too much about what I eat and how much I exercise.

However, it has been a useful gadget to show me that I am generally already following a good diet and exercise pattern. This is probably evidenced by the fact that my weight has not changed for decades. (I am passing the Lumen on to Hubby G, who is keen to sort his diet.)

10% discount with the code FIONAOUTDOORS. Buy from Lumen. (I receive a small commission for sales.)

More Like This

Kit

Review: Kathmandu Women’s SUN-Stopper Long Sleeve Top

Adventure

What to wear for hiking in the summer mountains

Kit

A beginner’s guide to running and hiking with contacts

Kit

Choosing a tipi tent for your outdoor adventure

Kit

New Flanci skorts, dresses, crop tops and matching neck sleeve/ head buff

Kit

Review: Horizon™ 300ml Vacuum Insulated Stainless Steel Rocks Tumbler