Between other diet-doctors wanting to put their own twist on the Atkins program (so THEY can sell books, too), food manufacturers wanting to cash in on low-carb products, and individuals who want to eat their cake and have it too, the original Atkins message has kinda gotten lost....
Wooo has been writing about what seems to work best for most people for weight loss, and what the current popular tweak to LCHF has become. Other people i know have dialed back on the ADDED fat with good results. I well know my own best formula for weight loss, too -- and it has nothing to do with drinking cream, adding butter or swilling EVOO.
The original message was, don't be afraid of natural fats. Eat like your great-grandparents, not like a late-twentieth-century diet-obsessed yuppie. The original fat-fast was a technique Dr. Atkins invented, then developed, with the purpose of forcing a person who was stubbornly glucose-burning into HAVING to burn fats for fuel because the usual over-abundance of carbs isn't available. In the decade since his death, things have changed.
Maybe the first person to suggest DRINKING oil was the creator of the Shangri-La diet. Before that, the only fat-bibbing i was aware of was the suggestion of real cream in one's coffee -- a substance known for suppressing appetite and providing energy all by itself. There's a reason you can just drink coffee for breakfast and not feel the need for solid food for several hours! It wasn't till much later that i heard anyone suggest adding butter to one's coffee ... but adding eggs as Sisson suggests is actually a very old idea. When i read Donaldson i also learned about the tradition from the British Isles of adding tallow to one's tea as a laxative, apparently another antique notion.
For overweight and obese people to burn their own body-fat for energy, they'll have the easiest success if they become "fat/ketone burners" rather than glucose burners. That's the magic of LCHF -- if our bodies still want to burn glucose, we'll get the constant hunger signals and be miserable and tired, but if our bodies are content to burn FFAs and ketones, they won't always be telling us to "eat eat EAT" like a bunch of old-world grandmothers! :-) The easiest way for us to know that we ARE fat-burners is to be in ketosis -- Atkins knew this, and recommended we check ourselves with the urine test strips which are cheap and easy to find and use.
But in this modern world, "more is better" to a lot of people. If you're seeing success by walking, surely you'll see MORE success if you run; if you can eat a 1500-calorie diet and make progress, you probably expect quicker weight loss at 1200; if you're doing well with pink pee-strips, you're bound to be an even better fat-burner if the strips are purple. ...However, if successful methods of losing weight were truly intuitive, there wouldn't be an obesity problem. The human body is not like a car, and the laws of physics are trumped by the laws of biochemistry when it comes to what actually WORKS.
With this philosophy, we find the original LCHF method getting tangled up with conventional wisdom! Is our goal to conform to a certain laboratory value for blood ketones, or to maximize burning of our own body-fat for energy...?
Just because we've managed to set fats/ketones free FOR burning doesn't necessarily mean we ARE burning them! If anything, a higher value on the pee-strips are superior to higher blood ketones because if they're in our urine that means we've already wasted "calories," spilled out energy! If fats and ketones are still in the blood, they're not gone yet, and fats at least can be sent to storage.
On a low-carb diet, we replace easily-stored energy with something which our bodies happily burn, then when the dietary source is exhausted, we switch to the endogenous supply without a lot of fuss (hunger). The more of the dietary source there is, the longer it will take to make that switch -- ie, start burning body-fat. So does it make sense to take in more than is required to satisfy the basic appetite, if you're trying to get rid of body-weight (as opposed to supplying fuel for a heavy workout)?
If energy-intake-restriction is a virtue (as in the popularity of the "fat fast" and its 1000-calorie goal) why do we want to add EXTRA dietary energy on an everyday basis? The most popular sources of added fat seem to be from dairy products, and they actually have problematic aspects for a lot of people -- even butter.
If you want to lose weight, first figure out how much protein you need or can tolerate. Then figure out how little carb you can get along with (some people need "none" and some people feel better with more). Finally, figure out how much fat you need so that you're not ravenous. If you find yourself losing so fast that your thyroid slows down and you feel bad (which has nothing to do with carb intake, but are merely starvation symptoms), add a little bit more protein and fat. Your weight-loss will slow down, but that's the tradeoff you'll have to make, if the lethargy bothers you too much.
As JanKnitz reminded us, ya gotta choose your "hard."