Nick Norwitz just posted a video eating a huge amount of butter per day, an extra 4K Calories per day, yet over a week he lost weight (slightly), his objective was to gain weight but lower LDL. So short term in his case and most people here who try low carb, one can eat almost any amount of fat and lose weight, but he suspects that in the long term it may well be a different matter.
Certainly, as a TOFI, when I had lost a bit more weight than I wanted (and got BG and HbA1C to normal), I found adding around an extra 600KCals per day in the form of cheese and nuts did the trick and I gained the extra pounds I wanted without compromising my T2D remission.
