On intermittent fasting you might be able to maintain your existing diet. You have to stay 0 calorie for 16 hours each day, that means basically nothing but tea/water during the fasting period. I read lots of stories and articles about the keto diet, and found many people felt initially much better for a number of weeks/months, but then negative side effects began to surface.
A lot of studies have shown constantly bouncing in and out of ketosis is the best way, and it creates a body capable of running on fat or carbs as energy. You can purchase ketosis urine strips to test yourself and see if your fasting is working. Basically pee on the strip before your first intended caloric intake each day, and you'll know right away. !ENGAGE 40