I was asked in an e-mail about ketosis testing and thought I'd share what I wrote.
There's a few ways to check for ketosis. There are at least three types of ketones running around in your body and each of the three most common testing methods tests for a different one.
There are Ketostix which you can get from your pharmacist. It's one of the cheaper ways but... it's not terribly accurate. It can be diluted by how much you drink and will often disappear after your body becomes more adapted at using ketones. These test for Acetoacetate.
Next is a device called a Ketonix which costs about $120 on Amazon. More initial cost up front but it can be reused over and over again. You just blow into it and it gives you one of four colors to tell how high it's measuring the Acetone in your breath. (blue, green, orange and red) I'd recommend the sport version over the standard version because it gives you more info. In addition to giving you a color it also flashes to tell you how deep into that color you are. i.e. orange that blinks twice is lower than orange blinking 9 times.
The third ketone body is beta-hydroxybutyrate. This is the ketone found in blood and is meausred much like testing for blood sugar. In fact I will usually do both these tests off the same finger prick so I don't have to stab myself more often than I have to. This is the most accurate meathod for checking how well you're doing in ketosis. But it is by far the most expensive. The meter I use is a Precision Xtra. It can test for both ketones and blood sugar. The meter itself isn't expensive but the strips are absolute piracy. I've seen them as high as $5 a strip! Shop around online for them if you go this route. I did find them for about $1.50 each here... http://www.ketosistools.com/collections/ketone-strips . That's the bad news. The good news is that you can get the blood sugar testing strips from Walmart relatively cheeply. The Precision Xtra uses the same strips as the ReliOn Ultima.
Now, having said all that there is one more far from scientific test I have always found useful. Take a mouth full of water, swish it around your mouth for a few moments and then spit it into an empty glass. Now smell. If you're in ketosis you'll be able to smell it.
As for when to test... the ketostix are usually best first pee of the day in my experience. Though ketones will generally be higher in the evening than in the morning. The other testing methods can be used at any time. The best way to get your ketones up and blood sugar down is to eat lots of saturated fats (butter, coconut oil, bacon drippings) few starches, sugars or grains, and modest amounts of protein. Low-carb, High-fat, Moderate protein.
For more indepth info on testing for ketosis I recommend Jimmy Moore's Keto Clarity.