Hi I am a qualified Nurse,
Ketosis can be very dangerous, as excess amounts accumulate in your blood and can be toxic.
The most important part of this diet is drinking water. It is very important to flush the ketones in your blood out, and so they are removed by your kidneys and excreted as urine. There is no danger to this diet if you are drinking in excess of 2 litres of water per day, (which we all are).
The ketones that diabetics excrete is similar to ours, but theirs is produced when they are getting too much insulin, and not enough glucose in their diet. We are not diabetics and our pancreas excretes normal amounts of insulin. Our pancreas is able to regulate the amount of insulin we require. So we do not have a large amount of insulin in our blood. Our weight loss is due to our diets being VLC, we are not taking in enough to sustain us and so our bodies are breaking down fat to make up our needs, and so we are loosing weight. As stated above we still need to flush this excess ketones out of our bodies with large amounts of water.
There is probably no harm in having a medical check-up if you are on this diet for a very long period, and if anyone is worried they can always have blood tests to check out the function of their liver and kidneys. Personally I feel that this diet is safe, common sense prevails if anyone is feeling unwell on this diet, more than the usual and normal symptoms of constipation, feeling cold and tired, and weak at times that they check themselves out with their GP's.
Don't get overconcerned, I think everyone here is sensible!