That's basically the Atkins diet (Keto) without enough nutrition. It'll function like a very short, very uncomfortable, malnourished crash diet.
You'll spend the first two weeks craving carbs and sugars like your life depends on it. It's awful. After that "break in" period, the cravings mostly go away.
But that's not all. So much as lick a piece of candy or chew on some bread, and you'll get a large dopamine rush followed by carb-craving mode again. If sheer willpower and deferred rewards are at all a problem for you, this might feel like one of the hardest things you've ever tried to do.
Edit: now that I remember, my grandma tried a "cottage cheese and grapefruit" fad/crash diet back in the 80's. Turns out that one has been doing the rounds for almost a century. IIRC, it doesn't work since it's easy to underestimate how insanely difficult this is to do.
Did keto for a while preparing for some on-camera work. I've never looked more cut and never been so miserable. 9/10 doctors do not recommend. The 10th one has an eating disorder.
I lost 40lbs on keto and after the first week of keto flu, I felt great. No sugar crashes, no energy level drops and overall, more energy than usual. I stopped after six weeks as I couldn’t deal with the lack of flavour and texture in the food I was eating. I reached a good weight that I've maintained, 7 years later.
One thing it taught me, was to reduce the amount I eat and to balance things out if I eat more carbs than usual.
I feel you. Hard cheese, bacon, and pickled eggs were my go-to. Anything with strong flavors. I did that for about a year and then stopped once I hit my weight goal.
In the middle of all that, I noticed that vegetables started to taste sweet as they do contain small amounts of sugar. Especially cabbage. I kind of miss that.
A workaround I employed was to eat lots of kimchi. Fermented foods like that contain sugar alcohols which taste sweet(ish), but are not digestible as such.
Been on keto for a decade with breaks here and there. Currently two pounds below goal weight. Feel great and blood numbers are excellent. Changed my life.
I thought I posted a reply but apparently I did not. Generally, my advice is that you need to treat everything like a really long journey and let yourself take breaks for birthdays or trips as appropriate, but get right back on track Monday morning.
I actually tried keto some years ago on a lark. I quickly learned to avoid supermarkets since I could smell all the sugar in the baking aisle halfway across the store. Before posting this, I didn't think such a high-protein, low-fat dirt could result in ketosis but I was educated by another user on how the process actually works.
I forgot about the smells. My sense of smell shifted to be way more sensitive to sugars and starches too - it was tough.
I didn't bother trying to track fat intake and wound up losing 2+ lbs a month that way; not bragging, but my goal wasn't all that big. I probably could have done things faster by cutting more fat, but it was already hard enough.
I was educated by another user on how the process actually works.
Fascinating, isn't it? It's like each of us is just full of survival mechanisms.