I am not sure about the science, but I can tell you anecdotally, that I no longer require a high amount of fat not to feel hungry on low-carb. I am considering a lower fat diet with the low-carb, as suggested on this forum, to assist with the last few pounds of weight loss.

The term "Fat adapted" is generally used to indicate that someone is no longer metabolically dependent on exogenous glucose (i.e. high carb intake) brought on by a low/no-carbohydrate diet that forces the body to synthesize glucose from alternate sources (fat & protein).

In this sense, if you become "fat adapted" eating low/no carb and then go back to eating a high carbohydrate diet, you will then return to being "carb-adapted" as free glucose is always burned preferentially. (Interesting side note, alcohol is actually burned preferentially to glucose.)

However, this doesn't rule out that one may have changed their overall metabolic environment (changes in insulin sensitivity, reduced bodyfat, etc.) that makes shifting back to a higher carbohydrate intake more amenable to continued progress in terms of bodycomposition, weight, etc.

I haven't tried eating a high-carb, moderate-to-high protein menu without fat so I can't speak to that.

I recently had some whole milk yogurt in the morning, then had a schedule that wound up causing me to opt out of eating any more that day. I can report that I never felt tired or hungry that day, woke up strong and normal-energy the next day and wound up not eating until mid-afternoon (other than the morning yogurt.)

That tells me I am indeed burning my fat reserves (which are ample) as required so Sunshine's opinion is plausible EXCEPT I assume you'd then need to have a food-to-energy deficit or you'd just burn the carbs you ate.

I think it's completely plausible. Our body's ability to store excess carbs is limited, so if we are eating lots of extra calories (both fat and carbs) via SAD, it makes sense that we preferentially burn the carbs and over time, down-regulate fat burning enzymes etc.

Once we get our metabolic flexibility back, as long as we don't overswing the pendulum (eat too few carbs), our body should be able to burn both fat and carbs equally (unless we're talking serious anaerobic activity).

From my lay perspective, it just has never made lots of sense to me to eat boatloads of dietary fat as long as I'm carrying around sufficient fat stores (like Nance, mine are ample). Instead, I eat dietary fat prescriptively: I make sure to eat fat that carries a healthy nutrient load (like pastured egg yolks) or some healthy fat (like coconut butter) for satiety's sake.