Are you sure that ketosis can alter metabolic things?

It is a perfectly natural state to be in when all said and done - although the name is like the state which diabetics get into which is very dangerous, it is not the same.

I can't think why being in ketosis should cause birth control to fail - there is no logical reason for it.

It is not an imbalance in your system, it is the way the system works, and the ketones are excreted naturally and efficiently as long as your kidneys are working properly.

Carbohydrates are not stored as starch in Human cells - that is what potatoes and the like do.

We convert carbohydrates to fat for long term storage, a process governed by the insulin we make.

Ketosis is just the fat being broken down as the process is reversed and the unwanted bits go through the blood and urine to be got rid of. That is how it should be. If that did not happen you could not use fat to fuel the body, it would just stay there for ever, with the energy locked away and useless.