DON'T BOTHER WITH THE KETOSTIX!
Here's a really useful post about them, from the Carblife website (which also explains why you should be drinking lots of water):
"I know how encouraging the use of ketostix can be - to see the stix change colour confirming that ketones are being produced is a big boost. After all ketones in the urine means that fat is being burned. However there is a lot of confusion about thier use and the reading we should get.
a) If you are eating very low carb then in order for your body to have energy it must turn to either fat or protein. This can either be from stores within the body or from dietary resources. However because the body can't fully "burn" protein for all its energy needs it has to switch to burning fat for it's main energy supply. This is obviously good news for the overweight.
b) Once the body has swtiched to using fat for fuel (which it has to do when low carbing), it produces ketone bodies as a 'by-product'. The body can then also use a varying amount of these ketones for it's energy needs.
c) The amount of ketones produced in the blood will depend on how much fat is "burned" for energy. The level of ketones can therefore depend on a number of factors:
--- The amount of exercise you are doing
--- The amount of fat available (not normally a problem with the overweight!)
--- The health of the metabolism.
d) However producing ketones does not mean that you will get a reading on the urine sticks. The amount found in the urine is only what the body can't use for its own needs. It's the excess that has 'spilled' over into the urine.
e) In some cases this can mean that your body is burning fat, and producing ketones but the stix don't change colour. This is due to your body using up all available ketones in the blood for it's own use, leaving none or very few to spill over into the urine.
f) This means that if you don't drink enough, two things can/will happen:
--- The quantity in the urine makes the urine very ketone 'rich', resulting in dark coloured stix.
--- The body will stop production of ketones to prevent levels in the body getting too high. No production ketones = no fat burned.
g) If you do drink plenty of water you are constantly flushing the ketones out and allowing more to spill over from the blood. Drinking plenty of water therefore causes the following to happen:
--- it allows more ketone bodies to be produced and therefore more fat to be burned.
--- the constant flushing out means that the ketone concentration in the urine is kept low and a light colour is normally seen on the stix.
h) However it is possible, in a few cases, to be drinking loads of water and still getting dark readings on the stix. This can be due to:
--- High amounts of fat eaten often shortly before testing.
--- The time of the test. Testing first thing in the morning would normally produce a darker colour than last thing at night.
--- High amounts of body fat are being burned - however this would normally only happen (but not exclusively) either at the very start of low carbing or during a visit from the whoosh fairy!
--- The body for some reason is not needing the use of the ketones in the blood.
In summary then - use the stix for encouragement but not to worry too much about the reading. If the stix are dark make sure you are drinking at least the right amount of water for your weight. In rare situations they will stay dark so realise they can be dark for other reasons. But check that the water drunk is enough. Oh, and restricting carbs to low levels will cause your body to burn fat and produce ketones.