Most chicken contains additional liquid added during processing. Carefully read the packaging. If you find that the chicken contains broth, it is illegal as commercial broths contain starches. Other chicken labeling will say something to the effect that it contains up to 5% water by weight from the chilling process. This is probably okay. If you’re in doubt, ask your butcher.
When I began the diet, it took me about six months to realize this. I assumed that when I was buying chicken, that was all I was getting. One day I read the packaging and found I had been eating illegal chicken without knowing it.
I became much more diligent at reading labels. I’ve leaned that you can never assume.
UPDATE 2.9.10: It’s been pointed out to me that turkey has the same problems as chicken. Read the label on virtually any frozen turkey and you’ll find broth in the ingredients. Try looking for a fresh turkey and talking to the butcher. (Thanks Penny!)