I can't see why BCAAs on a hypocaloric diet would inhibit fat loss.
The real issue in overweight people is the leptin resistance, which forces the higher leptin levels (and leaves them feeling hungry all the time).
Since they are secreted by the fat cells, the more fat you lose...the less free floating blood leptin you should have. Also it should help to reduce leptin resistance as well (so will lower carb intakes).
Leptin and Insulin are 2 hormones which are in itself not evil, but when the resistance builds to them....that is the real danger.
I use BCAAs pre/during workout and don't do any kind of protein shake post (maybe a glass of milk at best and then a meal which will be higher in carbs). I've also used BCAAs to sip on during an IF day.
I can't say I have seen any negative effects from it.