Lumen is a consumer-direct handheld device that measures CO₂ concentration in a single exhaled breath, computes the respiratory exchange ratio (RER), and reports a number indicating whether the user is metabolically in a fat-burning or…
In the full monograph
- What it is, and how it works
- What the evidence shows — randomized trials, observational data, animal studies, graded and cited
- Dose, form, and timing
- What to expect, and how soon
- Who should be careful, and what to check first
- The verdict
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