There are many myths about weight loss, but there’s one that’s particularly persistent.
“Most of my patients coming in for medical weight-management tell me, ‘I have no metabolism.’ Obviously, that’s not true,” says Jody Dushay, an endocrinologist at the Beth Israel Deaconess Medical Center and assistant professor at Harvard Medical School. “Metabolism is literally the function of every single cell in your body.”
In order to function, your body converts food into energy. It’s a complex and personal process, determined by your age, gender, muscle-to-fat ratio, exercise levels, hormone function, and more. Dushay says that blaming a “slow” metabolism for weight gain (or crediting a “fast” metabolism for weight loss) isn’t medically accurate—though your metabolism might differ from someone else’s, the pace is determined by what your body needs.
You also can’t blame your sluggish metabolism for weight gain later in life; as you get older, you move less, and moving less means you’ll lose muscle and gain fat. Generally, people with “faster” metabolisms, for lack of a better word, need more calories to sustain basic functions such as breathing and blood circulation. But having a faster metabolism doesn’t necessarily mean you’ll have a leaner body. In fact, studies show that people with bigger bodies need more energy for basic functions, so they tend to burn calories at a faster rate.
Complexity aside, however, when there’s a connection to weight loss, there’s money to be made. Naturally, there is a company attempting to help its customers peer into their own metabolisms to better understand them, and, ultimately, tinker with them to boost their health.
In 2014, twin sisters Merav and Michal Mor, both Ironman winners with Ph.D.s in physiology, developed the Lumen: a vape-like device that measures metabolism and gives recommendations on what to eat in order to improve its functioning. Lumen, which went on sale in 2018, promises users everything from easier weight loss to better moods, boosted energy, improved sleep, and greater overall health. The $250 price tag includes the device and three months of access to its app, or you can pay $300 for six months or $350 for 12.
As an active 26-year-old with a general understanding of fitness and nutrition, the potential to “hack my metabolism,” as the company claims, intrigued me. After coming across several social media posts about the Lumen, most of which appear to be advertisements from the company’s influencer program, I decided to give the device a try—as well as call up experts to see if there is any validity to the brand’s claims.
Once I received my Lumen in the mail, I downloaded the app and answered questions about my age, weight, height, sleep routine, menstrual cycle, and goals (I selected “healthy weight loss” for journalism’s sake). It was then time for my first morning measurement. I had to inhale from the device for four seconds, hold my breath for 10, and exhale into it for six while keeping a ball inside a circle on my screen. It took me about eight dizzying attempts before the app accepted my breath sample (these tests got easier over time). Gas, temperature, and pressure sensors in the device measured my oxygen consumption and carbon dioxide production. The Lumen takes this information and tells you on a scale of 1 to 5 whether your body is currently burning more carbs or more fat.
My first “Lumen level” rang in at 2, meaning my body was burning more fats—a sign of a “healthy metabolism” in the mornings, after workouts, and “optimized fasting,” according to the app. Nonetheless, I was immediately advised to have a “low carb day,” which, according to Lumen, is the first step in the journey to improving metabolic flexibility, or how easily the body can switch back and forth between fats and carbs. The company says this flexibility is critical to weight loss “because you can lose weight, but still not train your body to use the food you eat properly”; it’s why many people who lose weight tend to gain it back later, the company says.
For nearly two weeks, I did as the app suggested, measuring my metabolism as soon as I woke up, again before going to sleep, 30 minutes before and after exercising, and one to two hours after eating. I followed meal suggestions from the app as well; they included simple but limited recipes, such as a corn-tortilla wrap with chicken salad or pork with grilled vegetables.
I wanted to enjoy the Lumen experience, but it just wasn’t practical or helpful in ways that differ from other health trackers I’ve used, like an Apple watch and a FitBit. Two weeks is a lot to spend breathing into a device at so many various intervals, but the Lumen app advises that users should do this over months for the most accurate results and advice. Although most wellness goals require similarly lengthy dedication, I wasn’t motivated to keep using the device because the advice I received didn’t differ enough from my normal routines and what I already understood to be a healthy lifestyle. For example, it’s no surprise that a late, indulgent dinner would be followed by a recommendation for a low-carb meal the next day. (Though I did appreciate that the Lumen’s diet recommendations were based on macronutrient grams—fats, carbs, protein—instead of calories, which can ensure that you’re not going hungry in your attempt to lose weight.)
