Whether this diet is actually sustainable continues to be a hotly debated question. But for the most part, the general consensus seems to be that it's only safe up to a certain period (no more than three months). Making this a permanent lifestyle choice is not recommended as carbohydrates are an essential macronutrient. Women who are pregnant or anyone with gallbladder disease or liver disease should avoid attempting keto altogether. It's a good idea to work with a doctor or dietitian when starting the keto diet.