No, the physician warning is for diabetics due to the risk of ketoacidosis, which is what the strips are designed to warn against. Keto people using them to indicate a state of nutritional ketosis is not the intended use, and they are not the best guide for the keto dieter.

@kirkor what is the best method for testing, one seen that ketostix are not necessary but I don't want to spend money on a blood meter if it's possible to be confident another way

I like the ketostix.. At least for the first month or so, but just for motivational support.

A few things to remember though.. A high protein diet or not drinking enough water will both make the strips dark as you are passing higher numbers of ketones (higher protein than you need) or higher concentration because you're dehydrated.
**you can have dark strips without that being the case but I double check my numbers and drink a little more if mine are dark**

I say buy one cheap box and give it a try.. Its a cheap way to give yourself a thumbs up for staying on track...

..also, as your body keto-adapts you may not see positive strips.. Generally this means that your body is using everything you're eating efficiently and thus none is spilled into your urine.