I’ve been more active than ever in the last few years. And I thought I would write about Lumen, one of the tools that has helped me gain better awareness about my metabolism.

The pandemic gave us all a scare and motivated me to eat better and do more exercise. While I couldn’t go out much, I went out jogging almost every night and spent a lot of time on Clubhouse. One of the people listening wondered what the rhythmic noise was on one Clubhouse call, and it was the sound of my jogging feet.

I also started eating better, trying to cut out most carbs. I missed rice, and so that wasn’t easy. But during that pandemic time when everything was closed, I lost about 22 pounds. When the gym opened up, I went back and changed my whole routine. I still went maybe six days a week, but my workouts weren’t as intense as jogging. I lifted weights and did the treadmill or stairmaster. I proceeded to gain all of that weight back.

That’s where I was back in May when I started using this gadget call Lumen, a handheld device that measures a user’s metabolic activity through their breath. You inhale air through the Lumen device for 10 seconds and then exhale through the device for at least six seconds. Lumen measures my carbon dioxide levels to figure out if I am burning fat or carbs. You can measure yourself once a day or a bunch and the app will tell you whether you are burning carbs or fat.

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In the past, you could only get this assessment through some elaborate lab testing and the results never came back fast.

Burning carbs or fat?

Lumen gives you choices about when to measure your fat burn.

If you’re burning carbs, you’re likely burning the food that you ate. If you’re burning fat, you likely didn’t have too many carbs in your latest meal and you’re in a better position to lose weight. And if you combine that with having a good night’s sleep, you’re likely to wake up in a state of fat burn. It makes sense that if you sleep for a long time, you can fast for longer.

If that happens consistently, then you’ll probably wake up in a state of fat burn more often and lose more weight. If you eat late at night, eat too many carbs, or don’t get enough sleep, these are all things that can cause you to gain weight. Maybe this isn’t true for a lot of people, but I found it is for me.

So it was interesting to see how avoiding that waking up in a state of carb burn changed some of my habits. I wanted to wake up in a state of fat burn. So, as recommended by Lumen, I ate fewer carbs, I didn’t snack as much late at night and I tried to get more sleep.

For me, that was the basic steps for losing weight. In the last couple of months of my low-carb diet, I’ve still been exercising just as much and I’ve been losing weight. It’s fluctuated between something like four pounds lost to eight pounds lost. As promoted, Lumen helped me maintain a better metabolic balance, burning fat while sleeping and hitting a better fuel equilibrium while awake. You can adjust what you eat, how much you eat, and your activity to hit your targets needed for consistent weight loss.

Lumen also has some more advanced recommendations if you track your meals and what you eat. You can say what you ate and Lumen will count the protein and carbs for you. I found that exercise alone didn’t work. I had to control what I ate as well, and how much sleep I got.

If I didn’t stay on target, then I saw that I would wake up in the morning burning carbs. And then I might start gaining some weight again. It was all sensitive to my personal activity and I found there were immediate data-centered results in a good or a bad way depending on my behavior.

I can now get pretty instant access to whether my body is burning fat or carbs. And, with real-time data, I can make smarter decisions about what I’m going to eat or sleep or exercise. When I woke up with a Level 1 or Level fat burn, I knew that the decisions from the day before mattered in increasing my fat burn and weight loss, while waking in a state of carb burn from Level 3 to Level 5 meant I had eaten too many carbs. When I had a spaghetti carbonara for dinner, I woke up in a state of carb burn.

Origins

This all the result of Daniel Tal Mor, his wife Michal, and sister-in-law Merav. They created Lumen to measure your metabolic activity. They managed to raise $62 million in funding to create Lumen. So far, people have taken tens of millions of measurements with Lumen. They took a holistic approach.

You can tell Lumen what your goals are, like losing weight or building muscle. By measuring CO2 levels, Lumen can determine whether the user is burning fat or carbs, offer dietary suggestions, and basically help each user track the current state of their body and maintain a metabolic balance. With that guidance, users can prime their bodies to burn fat while sleeping, then strike a fuel equilibrium while awake.

I also tried out a glucose monitor from Dexcom a while ago, and it measured my blood sugar levels. When I ate carbs, the blood sugar levels shot up, but not so much as it would if I were a diabetic. Still, it was fascinating to see what effect certain foods had on my blood sugar.

Lumen is a big step in that integration, short-circuiting the cycle of ineffective diet and health trends. With a breath, the device breaks down how your food and exercise impact your metabolism, then offers a scale from 1 to 5 that charts whether your body is running on stored fat or the carbohydrates you’ve been consuming. Based on that reading, Lumen then offers recommended dining options with specific carb, fat, and protein macros to help rebalance your metabolism and get your body in proper alignment. Lumen wants to give you not just a device, but a bigger role in your personal health responsibility.

Lumen feedback

Lumen recommends nutrition plans for you.

Mia Johanna Dige, digital events specialist and metabolic coach at Lumen, encouraged me to take morning measurements with Lumen to see how sleep impacted my metabolism. She noted that hitting my protein recommendation would help me build muslce and feel full after meals. That should result in less snacking. She also noted that taking before and after exercise measurements would give me more insight into how to fuel myself when doing workouts or even just walks.

“Your device is going to learn your breath signature,” said Dige. “This is how different we are. Our metabolism is unique. And it’s the driver behind all our health goals. Metabolism basically is how our bodies are taking the food and the beverages we consume. Turning it into energy to sustain life.”

She added, “Our goal with your Lumen device would be to improve your your metabolism, your unique metabolism to the point where you are metabolically flexible. Your body is efficiently switching between using fat stores when needed and tapping into your carb stores when they’re available. And switching between the two fuel sources.”

My metabolic flexibility went up over a few months with Lumen measurements.

Your body is kind of like a hybrid gas-electric car in that way. Once you know how to balance your metabolism, weight management becomes a lot easier, Dige said.

“You’re able to keep a healthy weight, and you’re able to have more energy. Because our blood sugar levels are now balancing and our insulin levels are regulated,” she said. “We need all three macros, right? We need carbs, fats, and protein. But importantly, we need them in the right amount suited for our metabolism. Your carb intake and fat intake needs to be tailored to your metabolism.”

My results weren’t bad, given a limited time window for monitoring. I was pretty good about measuring every day, but only about once a day. My “metabolic flexibility” went up about 42% during the measurement window across a few months. My activity went up as well, as Lumen was able to access my physical data on the iPhone and Apple Watch. I did OK on sleep, but I’m still far below average when it comes to getting as much sleep as everybody else. I think the critical things was cutting most carbs, even though I wasn’t religious about this part of my diet.

Nowadays, I’m still going to the gym a lot and doing exercise. I’m snacking less at night and eating a lot fewer carbs. I found I had to be careful about what I ate on trips because I wasn’t getting as much exercise.

“Every time you travel, you are out of your routine,” Dige said.

Long-term diet, exercise and sleep

My activity in a two-week window in August.

Once a week or so, I can eat the carbs. But I know I have to return to healthier eating right away — at least given where my personal metabolism is. While my weight loss numbers aren’t impressive, I’m pretty sure my percentage of body fat has gone down as I’ve built up a lot of muscle. But to make more progress, I’ll probably have to take up running again.

Lumen tracked some improvements in a window of a couple of weeks for me as I ate fewer carbs.

It’s not just me. Lumen has been peer reviewed. In October 2022, a study done in collaboration with the endocrinology department at the Tel Aviv Sourasky Medical Center was published in the Obesity Facts journal. The study’s findings revealed how metabolism-based nutrition can reverse prediabetes conditions. Over 12 weeks prediabetic participants measured their metabolism using the Lumen device and followed its nutrition and lifestyle guidance which resulted in lower Hb1c levels, an average weight loss of 13 pounds and 3% body fat reduction.

It costs $299 to purchase a device where you can access the basics of metabolic measurement. You can purchase a separate subscription at $19 a month, with a free trial month, to access the rest of the more comprehensive features.

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