Oh! I just re-read your question
@RayCox! Sorry about that - I was approaching the cream question from a fasting point of view, not an intermittent fasting pov, and, I wasn't thinking about weight loss goals in particularl. My bad!
The posters above have already addressed the weight loss with high fat issue, ditto windows of eating periods, I believe.
Basically the only thing I have to add is the healthy fat is a really important part of a LCHF way of eating to attain and maintain a normal weighted body. I have watched folks who do the low carb without the healthy fat, for weight loss, as in I have worked with them, and it's not a pretty sight! Kept out of their way for sure, especially after having my head bitten off for suggesting salad without a healthy fat dressing was unspeakable! (I didn't use those words, but that was my point.) I make the mistake of thinking the visual on my own successful weight loss LCHFing and IFing (and fasting) is a good thumbs up on my words of wisdom in those situations, but in actual fact it may be a deterrant? in the non type 2 scene at least? a lot of folks don't understand the enormous attention we pay to the weight issue, as our health and life span depends on it so. But you do at least!
I personally don't count cream in an IF regime, for practical purposes. Especially if goal is weight loss. Re weight, especially as a type 2, focus on the carbs, is my own motto. I also say, fat doesn't make you fat. But that is a handy generalisation, and maybe is not true for everyone? But it is for me.
But, I say, eating healthy fat, and having some in a drink whilst not eating, is def part of a treating T2 with LCHF and IFing regime.