Kopi O is one of the few kopitiam drinks that will not wreck you. No milk, no condensed milk, just black coffee and some sugar. That sugar is the only thing adding calories, around 55 to 60 of them, and you can kill even that by ordering kosong.
This is the move if you love your kopitiam habit but want to keep the calories tiny. Compare kopi O at 60 calories to a normal kopi with condensed milk at 140 plus. Same caffeine hit, less than half the damage. Easy swap lah.