Works like this. Find out how many calories you need to maintain weight at current activity level. Then decrease by 500 or so. Out of the remaining calories, your protein should account for 1 gm of protein per pound of body weight and the rest should come from fats. Keep the fats to good fats, such as coconut oil, olive/grapeseed/almond/walnut/hazelnut. Flaxseed and fish oils are good too, but I don't like their taste. I will put 3 tablespoons into 60 gms of protein and have my protein shake like that at least twice a day. Then I will cook lean meats, etc and add in the oil from the above. I mix all of my oils into a big container like a sun tea jar with a dispenser and just pour into shake or measuring cup for use. I try to not have anything to eat 1-2 hours before working out and then wait 30-60 minutes after a workout and have just protein, no carbs, no fats. Then I have my regular meal about 1/2 hour after that.
For me, I use 1800 calories as my deficit range for losing body fat. I need 200 gms of protein a day so that is 800 calories, which means the other 1000 calories comes from the oils (about 111 gms of oil or roughly 8 tablespoons of oil.
I keep carbs to 30 gms or less during the ketogenic phase. IE the days with "no" carbs. For me, I go 6 days no carbs and then 1 day carbs.
On carb day, you replace some of the fats with carbs from any source, ice cream, breads, pastas, rices, etc (even fruits) The key is this, on carb day, keep protein amount the same, reduce fats and replace the "missing" fats with the carbs. Say you cut the fat intake by half on carb day. That means roughly 55 gms less on fats. At 9 calories per gm of fat that is 495 calories and at 4 cal/gm for carbs you need to have 124 gms of carbs. Believe me it is not hard to get to that amount of carbs quickly. Just do not go over total calories to lose weight.
Also, I have found that I will put on about 6 pounds of water weight during carb day and by day 3 or 4 of no carb day, I am back to starting weight and burning fat.
If you have a lot of fat to lose initially it will appear to come off quickly, but as decrease your body fat, the fat loss process will become harder however; during this process you will retain more muscle than you would on other diets. If you are starting at say 10% bf, after four months you should be around 4%-5% if you dieted correctly and it will take you every bit of that 4 months to get to that 4%-5% body fat.