Just curious if this is a thing on the keto diet. I started keto about a week ago and have lost 7 pounds (239 down to 232) and I’m pretty much never hungry anymore. I love it so far!
I don’t have any specific reason as to why I might do this. Was just a thought that crossed my mind. Does this mess up your body being in ketosis? Is it something that isn’t generally recommended or is it good to have a day like this?
i might could be persuaded to give the concept (ALL FAT DAY) a go … now my imagination is going as to what all i would eat ! 
Who wants to do some shots of olive oil? 
One would still be in ketosis as one is still burning fat, even if it comes from outside the body. Some people do “fat fasts” with no carbs or protein as it’s easier for them than totally fasting with no food at all. Better than nothing for hopefully improving insulin resistance.
In this day and age, just about anything is possible. If you don’t have it in your home, they don’t have it at the store, it’s likely to be at Amazon.com. If not there, Mr. Google finds the most obscure things for sale a person can imagine.
But I do have to ask the obvious question, why would you want to do that? (I know, you said you didn’t have a reason. But I still had to ask, even if only rhetorically.)
I’ve come to the point where I just want to eat real food. Eggs come in a handy combination of protein and fat. Meat is similar but varies according to what kind, how prepared and what added to.
I sometimes wonder what we do to ourselves when we force things like “nothing but fat Tuesday”… or whatever.
Really was just a thought as I was figuring out what to eat over the weekend. I’m not even sure what I would eat to completely avoid protein.
I pretty much haven’t had any hunger since like the second day, so it is feeling weird to eat in general now.
If our objective is to lose weight by burning our stored body fat, and we eat a lot of fat, wouldn’t our bodies choose to burn the dietary fat before it would bother to call in the stored body fat?
that question is not as simple as it may seem. Read Obesity Code by Jason Fung. Its about hormones, and not just how much you eat. If you are fully fat adapted, your body will signal satiety long long ,one before you overeat fat (for almost all folks - there are exceptions) Now, if your insulin has ben lowered due to keto/fasting/whatever - your body will have access to body fat, and the excess stored fat will get mobilized pronto, since th body knows not to hang on to that.
Lots of people have done it. It is what Dr. Atkins recommended for the seriously metabolically resistant. He suggested 5 ‘feedings’ of 200 calories each worth of fatty food with minimal protein. He had some suggested foods- macadamias, cream cheese, cream, eggs yolks and mayo, and some other things.