My key to determining if a hen is truly broody is that she needs to spend two consecutive nights on the nest instead of roosting in her favorite spot. I’ve had some display most of the signs of being broody yet fail the two consecutive night test.
Before a hen goes broody or even starts to lay she stores up a lot of fat. Most of that is around the pelvic area and is called a fat pad, but the fat is all through her body. That is mostly what she lives off of when she is broody. She still needs to eat and especially drink, but most broodies only come off the nest once a day to eat, drink, and poop. In hot weather I’ve had hens come off twice a day for an hour each time, but in cooler weather I’ve had hens come off once a day for only about 15 minutes. Each hen is different. I’ve never had one starve herself to death, though some people toss them off the nest once a day to give them a chance to eat, drink, and poop. That’s just never been necessary for me. A broody will lose a lot of weight while she is broody but that is practically all fat stored for that purpose. It doesn’t hurt them until that fat runs out. That fat should not run out for several weeks. They were designed that way.
The best way to break a broody is to put her in a raised wire-bottom cage with food and water. Leave her locked in there for three full days. The wire bottom allows cooler air to hit her bottom, which helps. On rare occasions I’ve had a hen go back to her old nest after the three days, so I just lock her up in that cage again until she is broken from being broody.
