Diabetic Ketoacidosis is well documented in diabetic people[1], alcoholics, and in conditions of starvation[2] and the mechanism is the same. Ketone tests were developed for this purpose. Note starvation there, where the body starts using its own fats for energy. Here's a case report of it happening to someone on a ketogenic diet[3].
The body does that under circumstances of low calorie intake. The case study I posted shows a person developing keto acidosis just from following a ketogenic diet, it’s a well documented risk of ultra low carbohydrate diets if you bother to look. It happens frequently in people using these diets to treat diabetes, it just happens to be less dangerous than Type II diabetes.
What of them you need, you can make it, gluconeogenesis and such. Proteins on the other hand...