The Keto-200 diet is one that I just invented. I am not a doctor or sports nutritionist, and am only going off of my limited personal knowledge and experience. It is a high-fat, medium protein, low carb diet. It is very simple, flexible, and should be effective for weight loss. It does involve a modified form of calorie counting.
Here is how it works. It uses a point system inspired by Weight Watchers. You get 200 points per day to "spend" on food. (You can try a lower point amount and it may work better, but this is what I am going with). To calculate points, add up the carbs in grams, subtract the fiber in grams and add the protein in grams. Ignore the fat content.
For example, I just ate a protein bar. The label says that it has 190 calories, 12g fat, 14g carbs, 5g fiber, and 10g protein. So this has 19 points (14g carbs - 5g fiber + 10g protein).
My theory is that for weight-loss purposes, carbs and protein are basically equivalent - they both raise insulin and they both have 4 calories per gram. And that eating fat does not make you fat. And, most controversial, and I have NO evidence to back this up, is my claim that, for weight-loss purposes, carbs, in limited amounts, are not harmful, and furthermore, too much protein causes weight gain. I believe that there should be no preference given to protein over carbs, and there is no reason to limit carbs, up to the point limit. So if you like carbs, eat carbs, and if you like protein, eat protein. But don't demonize carbs, and fat is your friend.
I will try it myself and provide further thoughts.
Disclaimer: Pregnant women, kids, and diabetics should not try this without checking with your doctor. It will not work for body-builders, who need more protein.
Update: Protein does raise insulin, but not to the extent of carbs. I think a better number would be 1/4 the amount of protein grams, rounded up. And fat does have a minor effect, although much less than either of these. So maybe use 1/10 the amount of fat in grams, so there is some "cost" to fat.
So, maybe have a limit of 100 points, where a point is a gram of carbs, plus 1/4 the grams of proteins, rounded up, and 1/10 the grams of fat, rounded up. A 2000 calorie ketogenic diet composed of 75% fat by calories, 20% protein, and 5% carbs would have 166g of fat, 100g of protein, and 25g carbs. This would "cost" 67 points. That sounds about right to me.
Update 2: There is a school of thought that once enough carbs are consumed, (and this number is different for each person, but generally is in the range of 20g - 100g), that eating more fat will not cause you to go into ketotis. So just focus on the "antiketogenic" line, which says that protein is antiketogenic at 0.58. I think there should be some preference to protein, although not to the extent of ignoring it, so I will use 0.5 as a ratio, also for simplicity. So revised formula:
A = C + P/2 + F/10
where A is a "point" (meaning antiketogenic), C is net carbs in grams, P is protein in grams, and F is fat in grams.
Update 3: I think 120 "points" is a good maximum number for a day, so I am going to call this the Keto-120 diet. For target macros of 80g protein, 20g carbs, 120g fat, this would be 1,480 calories per day (using 72 points) which is a reasonable target for a diet. I personally believe that carbs don't have to be limited that much, so going to up 60g in carbs would make this 1,640 calories, still a reasonable target. Women should eat less and perhaps use 100 points as a target.