How Does Lumen Work?

More specifically, the Lumen calculates the respiratory exchange ratio

(RER) which indicates the fuel source the body is predominantly burning. If there's a high carbon dioxide concentration, it means carbs are predominantly used. If it's low in carbon dioxide, the body is in a fat-burning state.

Is Lumen actually good?

“Lumen's technology has been scientifically proven to accurately measure metabolic fuel usage when compared to the gold standard (RER) for measuring metabolism in multiple validation studies.” More specifically, Lumen says that when measuring metabolism, its results are comparable to that of lab-based RER measurements.

How often should you use Lumen?

You need to use the Lumen everyday for at least a month to get your flex score (a big commitment), because it's determined by your daily morning measurements and measurements after high-carb meals. The score ranges from 0 to 21, and I got a 6.7, which means I have low flexibility.