Nicotine has the following benefits:
Theoretically, the healthiest thing a smoker can do is to totally give up using nicotine in any form. But does reality conform to the theory?
The official list of nicotine withdrawal symptoms in the Diagnostic and Statistical Manual (DSM-IV) includes depressed mood, sleep disturbance, irritability, anxiety, difficulty concentrating, restlessness, decreased heart rate, and increased appetite or weight gain. These symptoms are supposed to peak within a day or so and disappear altogether after a couple of weeks. However, researchers have found that in some groups of quitters, symptoms do not dissipate and can, in fact, worsen as time goes on. 
The problems with concentration, memory, and mood make it difficult to fulfill responsibilities of daily living. How many employers are willing to overlook impaired job performance for weeks or months at a time? What effect does prolonged irritability that sometimes escalates into anger have on relationships with family, coworkers, and friends?
For many would-be abstainers, the Catch 22 is that some improvements in physical health???for example, better lung function???must be paid for with possibly permanent declines in cognitive and emotional health. Is it any wonder that so many relapse to smoking within a few days of quitting?
For those who do manage long-term nicotine abstinence, the picture is not 100% better in terms of physical health. For years the medical community claimed that smokers only gained 5 pounds after quitting. More recent studies reveal that the average weight gain is closer to 5 kilograms (11 pounds), accompanied by an average increase in waist circumference of 3.88 cm.  In 13 percent of women and 10 percent of men, weight gain exceeds 28 lb. The weight gained with smoking cessation is very resistant to weight loss interventions. 
Smokers who become nicotine abstinent develop hypertension at a higher rate than continuing smokers and those who are at risk for diabetes develop that disease 26% more often than continuing smokers. 
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