I have written this before but it's worth repeating. The keel bone test will tell you nothing worthwhile.I don't know if it was color or flavor but it was an unambiguous preference! The store only had fruit punch or lemon flavor so I got fruit punch. I am skeptical that she really needs it TBH because when I let her out she does go scratching around outside and eats stuff (not commercial food of course!).
I really need to learn this whole keel bone thing. I felt all of them this morning and they all feel the same degree of sharpness. Is it possible I am starving all my chickens? I don't even give them much in the way of treats so they mainly have commercial food and what they forage.
I do give kitchen scraps and I use sunflower seeds to bribe them to come in to be locked up if I am worried about hawks or am going to be away and once a week they get my left over Thai food rice.
You need to establish a chickens median weight over time and judge wieght loss and gain from that.