Underweight chicken

[SablethePoot]

Hey all!
New BYC user here
I have a polish frizzle who is quite underweight her breast bone is very prominent and her thighs are skinny’ though her crop is always full at the end of the night so I know that she is eating.she is perfectly fine in terms of behaviour and being herself,food is available all throughout the day and they occasionally get corn and worms.What should I do to help get some weight put on her do I give extra corn or encourage her to eat more?

 

[sourland]

Have you wormed your flock recently?

 

[SablethePoot]

Have you wormed your flock recently? (For context we bought 3 chickens for my original one that was the only one left of 3 so I currently have 4) Not yet since we have only had the new 3 for a month and they were on a different type of food before we got them and I’m unsure if it was worming food