Benign ketosis is a state induced by low carbohydrate diets, where the body burns fat as its main source of fuel instead of using carbohydrates, which are generally initially stored in the muscles as a substance known as glycogen. It is called benign ketosis because it is a safe and healthy condition, rather than the ketosis that diabetics experience, which is not benign.

As the body burns fat, it produces a by-product called ketones. Ketones are released from the body through urine and lungs. Ketones are the reason that one of the most documented side effects of the Atkins diet is that it can make people’s breath smell a bit strange: Ketones have a sweet smell, almost like pear drops, which is occasionally note on breath (this is not a foul odor like general “bad breath”, but it can be strong (sugarless gum or strong peppermint mouthwash usually masks it).

Some degree of benign ketosis has to occur for the low carb diet to work as it shows that the body is running out of fat. It will normally be induced within the first three days of following a low carbohydrate diet, as at this point the body will have depleted its remaining glycogen stores and instead have switched to burning fat.

Ketone testing is the best way to see if the Atkins diet (or another low carb diet) has worked and to what extent you are experiencing ketosis.

Ketosis test sticks, often called Ketostix, are available at most drug stores. These are typically used by diabetics to detect the type of non-benign ketosis that can accompany their condition. If you are on a low carb diet, it may help to purchase a pack of test sticks to help you see when you enter ketosis and how intensely ketosis is occurring. The sticks are inexpensive and generally come in packages of 120. You can buy Ketostix without a prescription.

To test for ketones, simply pee on one of the test sticks (like doing a pregnancy test). If ketosis does not occur, nothing will happen, but if it does, the rod will change a range of colors from pale pink, showing trace ketones, to very dark purple, showing deep ketosis. There is a table on the Ketostix package to show you the different colors and the amount of ketones it represents (although note that the packaging is designed for diabetics, so it will tell you that the darker the strip becomes, the more dangerous it is. it’s – since your ketosis is the benign type, actually the darker it is, the better your diet works).

You may want to experiment by testing at different times, you will see that after exercise the sticks tend to get very dark as the fat has been burned, producing ketones, while exercising.