I thought in ketosis it wasn't energy expenditure, the liver causes fat to break down and pass through your bladder? ... maybe I have that all back to front though :\ Maybe ketones pass through your bladder and they also break down fat cells...

That sounds vaguely like diabetes.

In the absence of metabolic disease, the body breaks down fat to use the resulting energy. Think about it evolutionarily; "there's no food right now, time to jettison my energy stores"?

Ketosis is a pretty weird state brought on by lack of carbohydrates. The liver starts producing ketones, ketones rapidly breakdown fat cells to boost blood sugar.

It is mostly unrelated to diabetes as that relates to insulin response.

Blood sugar is not boosted by ketosis. Ketosis can occur as a result of low insulin (in which case blood sugar will be high).

https://en.wikipedia.org/wiki/Ketosis#Mechanism

http://www.diabetes.co.uk/blood-glucose/ketosis.html