According to experts,nicotine,the substance which creates smoking addiction,activates receivers in the brain which signal smokers when to stop eating. The scientists from Yale University identified the reason why many people grow fat after they quit smoking.They claim that nicotine activates several cells within the brain,including the receivers which indicate smokers when to stop eating once they donít feel hungry anymore.For this reason it is very likely for a person to get some extra weight after giving up the nastyhabit of smoking. Researchers came to this conclusion after studying the effects of a substance related to nicotine on lab mice.They concluded that the mice ate less when that substance was given to them.This is a possible explanation of the fact that nicotine addicts donít feel the sensation of hunger when they smoke.Scientists say that nicotine attaches to several receivers from the surface of the cells and triggers the state of addiction in a certain part of the brain,but when it comes to gaining weight,they also realized that both nicotine and the substance used in the experiment activate another receiver,different from those who create addiction.This receiver is situated in the hypothalamus,an area of the brain where the appetite is controlled. For many smokers the fear of gaining extra kilos represents a good pretext to keep on smoking.Cigarettes represent a powerful drug which accelerates the metabolism,contracting the blood vessels and accelerating the pulse.According to specialists,once a person quits smoking,the metabolism becomes slower,and the appetite increases.The main explanation is that the body suffers a shock in the absence of nicotine which diminishes the appetite. Anyway,the risks of smoking are much higher than those of gaining weight;they include the high probability of getting a heart disease or cancer,and scientists say that people who quit smoking usually gain about 4-5 extra kilos,a weight which can be lost in a few weeks with physical activities,but the benefits of quitting smoking are much bigger than the disadvantages,so people who donít have the will to quit giving as an excuse the fear of growing fat should think twice and finally quit if they want to live longer.Good luck and no more smoking!