Disclaimer: None of the information in this article constitutes medical advice. All statements are merely the opinion of the writer(s). We recommend that patients follow their doctor’s guidance in regard to metabolism and weight loss.

Lumen is a tech company with a bold claim: that a breathing device can help you “hack your metabolism” to increase fat loss, lose weight, and boost energy naturally. The product has been featured in major publications like Entrepreneur and TechCrunch.

But is Lumen proven to work? What is "metabolic flexibility" and how does it overlap with weight loss and overall health? How do real Lumen users rate and describe the effects of the device? And what does a dietitian have to say about Lumen?

In this article we’ll answer all of these questions and more, as we explain if Lumen has been proven to work in clinical studies, and share our thoughts about whether or not it's likely to be effective for weight loss.

We'll also feature unsponsored customer reviews of the brand, and share a video where a registered dietitian (RD) explains her opinion on whether or not Lumen is likely to work.

Does Lumen Cause Weight Loss? 

Lumen’s value proposition centers on a concept called "metabolic flexibility," which refers to the body’s ability to shift between burning fat or carbs as a primary energy source.

Metabolic flexibility is a legitimate medical theory.

A medical review published in the Cell Metabolism journal analyzed how metabolic flexibility is associated with health and disease.

The study authors described how metabolic inflexibility may contribute to poor health. Insulin resistance occurs when the body’s metabolism of carbohydrates breaks down and becomes less efficient due to beta cell dysfunction.

A healthy person has no issue switching between fat or carbs as a source of energy, but an unhealthy person may struggle with either or both.

A 2018 medical review explored the topic of metabolic flexibility in more detail, explaining many factors that influence it. Gastrointestinal peptide release, natural hormone production and mitochondrial function were all listed as factors that can affect metabolic flexibility.

The second review is more interesting than the first, because it also outlines research-backed ways to improve metabolic flexibility. Lifestyle interventions are effective for countering metabolic inflexibility, according to the researchers.

Exercise (both aerobic and anaerobic), normalization of weight for overweight and obese individuals, interruption of sedentary behavior like short walks during work, and supplementation of certain amino acids like l-carnitine were all suggested to improve metabolic flexibility in the above-linked medical review.

While the general concept behind Lumen is legitimate, we cannot identify any medical research suggesting that Lumen optimizes metabolic flexibility in healthy individuals beyond the healthy lifestyle changes described above.

Basically, the standard healthy lifestyle recommendations most people are used to hearing seem to be the biggest factors in enhancing metabolic flexibility: eating healthy, exercising and avoiding a sedentary lifestyle.

Lumen claims to measure carbon dioxide levels in the breath to determine a “flex score” that shows consumers how flexible their metabolism is. It’s important to note that neither medical review we examined mentioned carbon dioxide levels at all.

In our opinion, whether or not Lumen can effectively track various indirect measures of metabolism doesn't matter, because it's illogical to pursue weight loss based on those measures.

We do believe Lumen is likely to be effective at tracking what the company claims it can track, but what's the point of doing so if it cannot improve health beyond making healthy lifestyle changes like eating whole foods and exercising?

Dietitian Shares Concerns About Lumen

A YouTube creator and RD named Abbey Sharp shared some of her concerns about Lumen in a video with over 100,000 views:

Questionable Health Claims on Lumen Site

Lumen makes some uncited health claims on their website that we find to be questionable, including the statement shown above.

While Lumen is clinically shown to accurately measure whether carbs or fats are being used as a source of fuel, we can't find any evidence to support the statement above.

Why does it matter whether a person is burning fat or carbs for fuel if data from Lumen can't use this information to improve health? The entire premise behind the company is confusing to us.

It's worth noting that Lumen was shown to support optimal metabolic function in adults with pre-diabetes in a 2023 clinical trial, including reductions in weight.

We also have concerns about the company's claims of enhanced fat burning and weight loss, because we can't locate any clinical trials showing that Lumen causes weight loss in individuals without pre-diabetes.

If someone buys a phone app that buzzes to tell them to go for a run, the phone app doesn’t “melt away fat,” the fact that they went for a run does.

Lumen is the phone app in this analogy; a device that may suggest healthy practices, but doesn’t directly cause any physical changes, so we consider it to be a waste of money and disagree with the health claims made by the brand.

Real People Try Lumen

A YouTube creator called "Fitness & Finance" reviewed Lumen after three months of use:

A TikTok creator named "sydneystaubin" claims to have lost 19 pounds using Lumen:

@sydneystaubin Lumen Check-In DOWN 19 LBS! so proud of my progress! #weightloss #lumen #lumencheckin #athomeworkouts #morningroutine #weightlossjourney #weightlossprogress ♬ original sound - SYDNEY ST-AUBIN

Our Clean Weight Loss Picks

Ceylon cinnamon was described as "an effective anti-obesity agent" in a 2022 meta-analysis. The study authors concluded that effects were greater at doses at or over 3 grams daily.

Illuminate Labs Ceylon Cinnamon Extract is our standardized Ceylon cinnamon supplement which is third-party tested to ensure purity and potency.

Dietary fiber was shown in a medical review published in The Journal of Nutrition to cause 16 pounds of weight loss in 6 months when combined with moderate caloric restriction (750 calories per day below baseline).

MBG Organic Fiber Potency+ is our top fiber pick because it's certified organic, provides 7 g of fiber per serving and costs under $1.85 per serving at the time of updating this article.

Both of the products mentioned in this section are entirely free of additive ingredients that we consider to be unhealthy.

Pros and Cons of Lumen

Here are the pros and cons of Lumen in our opinion:

Pros:

• Clinically shown to accurately track data
• Clinically shown to support metabolic health in adults with prediabetes
• Non-invasive
• Unlikely to cause side effects or harm
• Sleek design
• May motivate some individuals to lose weight
• Company's general claims about metabolic inflexibility are accurate

Cons:

• We can't find any clinical evidence this device causes weight loss in adults without pre-diabetes
• Expensive

Conclusion

We do not currently recommend Lumen because it's relatively expensive and we can't find clinical evidence suggesting that this device supports metabolic health in adults without pre-diabetes.

Lumen was recently shown to improve metabolic function in adults with pre-diabetes, so for that patient population, we recommend speaking with your doctor about whether or not the device may be worthwhile.

We commend Lumen for continuing to fund clinical research published in peer-reviewed medical journals, and if a trial emerges showing Lumen to be effective in adults without pre-existing conditions, we'll consider recommending it.

Metabolic inflexibility appears to be associated with dysregulation of metabolism and overall health, and there are free lifestyle changes that health-conscious individuals can make such as increasing exercise and normalizing weight (for those who are overweight or obese).

One benefit of Lumen is that it's a physical device which is non-invasive and is therefore unlikely to pose any health risks or cause side effects.

We haven't come across any convincing clinical evidence that it matters whether healthy individuals follow a low-carb or a high-carb diet.