Being in ketosis because of a LCHF diet is perfectly normal and safe. The only thing to watch out for is when first transitioning into ketosis there is a potential for electrolyte loss.Is there such thing as a healthy state of ketosis? Does a low carb - high fat diet put you in this state?
But will I gain weight if all I eat is fat?Most of us who do LC/HF try to achieve healthy ketosis everyday. We usually do this by eating under 50 carbs a day, sometimes less. It also takes replacing the carbs with fat. Healthy Ketosis means you are burning fat for energy. A lot of people confuse having ketones with something called DKA. DKA happens when your bgs are very high and you have no insulin on board to deal with it.
1. You would not be eating 'all' fat, only a high percentage.
No, weight loss or gain is more complex than just what you're eating. As to whether or not ketosis is healthy in the long term I'm not aware of any long term studies that answer that question. However, the ketogenic diet itself has been around for a long time, it was used in the early 1900s to treat childhood epilepsy, and if there any major health issues with it I kind of think someone would have spotted them by now. And on the flip side, I think it's pretty clear that there are long term health risks for the typical western high carb high sugar high calorie diet. Not that this makes ketogenic diets safe, but as an option it's hard to do worse than the typical western diet.