[Science-ish] Measuring Ketones, Fat Adaptation vs. Ketosis (23 min read): In explaining why & how to interpret your ketone levels, Amy does a great job of outlining the difference between ketosis and being fat-adapted. Once you establish a correlation between your ketone levels and good things happening to your body and brain, you don’t have to keep testing. Once you know which foods and activities work best for you, stick to them, and check in once in a while.