I had the same problem with my very sweet and docile buff just a few weeks ago. She was broody for about 7-8 weeks. I too had to put water and food near the nesting box as I saw her lose weight and appear listless.
I tried all the things mentioned in earlier posts. This is what I did during the last week she was broody. I think the "trick" for her (and me) was a combination....or maybe she just gave up. Fortunately, I was home the entire week so I was able to do several things at once. All of a sudden, she got off the nest, simply joined the rest of the flock. She has since gained weight and appears quite normal.
1. No eggs under her at all. (I would take away the plastic egg from your hen) I made frequent trips to ensure I removed any eggs laid in her "nest".
2. I physically took her off the nest 5 or 6 times a day, walked about with her and placed her some 20-30 feet from the coop so she had to at least walk back, passing food, water and the other hens. (I let mine free range when I am home, so the other girls were out and about)
3. I did the water bath....don't know if it worked that week as I had done it in the past. She sure looked pretty.
4. I made sure I got her out when I gave the girls their treats so she would eat. If I fed them in the pen, I made her join the others. I forced her to participate whenever I could.
5. I checked her frequently for mites, etc. She didn't seem to mind all the extra handling, may have even enjoyed it. I would take her out of the coop, away from the nesting boxes and check her out, make her walk back.
6. I was not ready to raise chicks nor did I have extra housing, so fertile eggs were just not an option for my situation. If I had the necessary set up, I might have tried that again. Once, about 5 years ago, when I inheirited my first hens, I ordered fertile eggs from
EBAY for my 2 broodys. The eggs never hatched, but as I look back, I am sure it was due to my inexperience.
Hope this helps you. Good luck. What we will go through for our babies.....
Anne