I'm a bit hesitant to go with any sort of "only eat this" diet. It just sounds scammy and gimmicky.
But the eggs and steak diet someone posted here really intrigued me! Mostly because it is a way of doing zero carbs without fasting.
I haven't gone in hard on anything, but for a couple of weeks I focused on
A) eating high protein/fat (mostly meats and eggs),
B) eating just one meal a day, with a light snack and
C) drinking a lot of water (the way I used to!).
D) NOT EATING LATE (this is a problem for multiple reasons, but if your big meal is breakfast or lunch, you are likely to be in ketosis when you wake the next day).
Haven't weighed myself, but the stubborn belly fat that didn't seem to go away with exercise shrank roughly in half.
It's basically a plan to force your body into ketosis, making it burn fat, while simultaneously giving your body little to no carbs to burn even if it wanted to. I'm going to rotate one week on, one week off of this and see how it goes. But I am now much more positive on carnivore diet which sounded ridiculous to me before (I still mostly believe a balanced diet of a number of different foods is healthy--but as we age and metabolism slows I think an intermittant carnivore diet is very beneficial.
I didn't just focus on steak and eggs, but instead just opted for high fat / high protein foods and cut out full carbs / desserts etc.
For example my snack might be yogurt with fresh berries. I use the 10% milkfat Cabot yogurt (it makes even the old Fage yogurt I used to use seem weak and tasteless!)
This is without artificially restricting my diet, other than eliminating dessert. I still ate a salad or 2, some popcorn, etc. Just generally choosing ONLY FOODS whose FAT and PROTEIN are BOTH greater than CARBS. I think the purest form of this is ONLY eggs + steak, but it's also a bit extreme for me.
The interesting thing is even with one meal a day I AM NOT HUNGRY! That 10% fat yogurt is filling!