There is a correlation between level of acetone measured in the breath and fat loss. More from the study (Joseph C. Anderson. Measuring breath acetone for monitoring fat loss: Review. Obesity (Silver Spring). 2015 Dec; 23(12): 2327–2334.) notes in one study that:
1 lb/week of fat loss corresponded to BrAce = 67 nM (1.7 ppm). Every ∼40% increase in BrAce (e.g., from 67 to 94 nM) corresponded to an additional ∼0.5 lb of weekly fat loss.
Another study noted that:
Fat loss and BrAce were greater for experimental subjects than controls.
Maintaining a BrAce= 85 nM (∼2.1 ppm) corresponded to a fat loss of 227 g/week (0.5 lbs/week).
Relating to the Low Carb
Adults in nutritional ketosis have BOHB ranging from 0.5‐3.0 mM, which corresponds to a breath acetone range of 4 to 30 ppm.