I test fasting, once per week on a Sunday morning. Just for curiosity’s sake more than anything - if I weren’t burning ketones for fuel I’d have died a long time ago
It’s also important to understand that you shouldn’t go chasing after bigger numbers. Measuring ketones only tells you that which your body currently
isn’t using. As you become better adapted to burning fat as your primary metabolic pathway, your cells will become more efficient at using ketone bodies for fuel in lieu of glucose, and the numbers will often get lower when this happens. After a while, if ketones drop alongside glucose then that is optimal.
For reference I almost always test at ~3mmol