Whether young or old, some people smoke to control their weight. Smokers, on the average, weigh seven pounds less than non-smokers. Smoking reduces a person's appetite. It lessens his/her sense of taste and smell. This could be why ex-smokers gain weight after quitting cigarettes. Food tastes and smells so much better.
Finally, there are people who say they love to smoke. Smoking gives them pleasure. It just makes them feel good.