If week to week they are losing weight, then you do want to feed them a bit more than you are now.
Mine are outside all day, and have a few things that are still alive that they can nibble on
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On days when I work, I give them the one serving (about their size), mist it, and leave it all day.
If I am around, I give them a smaller amount in the am, then give them a few extra things in the later afternoon as I find them in the yard, like a squash blossum, grape leaf, etc. That way they have the chance to graze some days, rather than have to eat everything at once.
I also skip 1-2 days per week (not that they like it). But I would adjust this if they were losing weight.
