Some people never show ketones in their urine and still loose weight just fine. During the first two weeks I showed ketones, after that I didn't (and I've been in induction for 12 weeks). It really doesn't mean anything as long as you are following the diet and dropping pounds and/or inches. Also, note that ketones only show up if your body has excess ketones. If you are very active and exercise strenuously, you may never show ketones.