One reason so many homeless people smoke: it suppresses the appetite, making it easier to cope with being underfed. Sometimes when people stop smoking and gain weight because of it, they really wrestle with the question of whether or not it is worth it. I have had women tell me that the hardest part of quitting was watching their weight go up. It made it really hard to stay the course because women are given so much hell in the US about how important it is to be thin.