Ketones in urine

What does it mean when ketones are found in the urine?

"Higher levels of ketones in the urine indicate that the body is using fat as the major source of energy." -- from en.wikipedia.org/wiki/Ketonuria

The Paleo Diet and many similar diets, such as the Candida Diet and the Lyme Diet, can be ketogenic because they seek to reduce or eliminate carbohydrate-rich foods.

There are also other causes of Ketonuria...see the above link for more info.