I'll be following this one with interest.
My experience is that a wormy animal will keep up or increase its regular feed consumption but lose weight at the same time, the worms eating up the difference.
Similar, but not exactly the same with laying. Without additional light, they will slow down their rate of lay as the length of daylight decreases, but that would be a matter of them consuming the same amount, converting more of their feed to staying warm rather than producing eggs. If, as I do, you do give them auxiliary light and they are keeping somewhat up to their usual producion of eggs, you should be seeing an increase in feed consumption. Mine will eat more on cold days.
If yours persist in eating less and start not to thrive, it'd be time for a call at least to the vet.