The presence of nicotine can raise a person’s basic metabolic rate while the sudden absence of nicotine can lower a person's metabolism. The latter occurs in those who have recently quit smoking or dipping, and it can take up to a year for the metabolism to get back to its normal rate. The effects of nicotine on the metabolism are a product of the increase in blood pressure and heart rate that occurs when nicotine enters the body as well as the increase in adrenaline production.
The moment nicotine enters the body, the blood vessels constrict, increasing blood pressure and making the heart beat up to 20 times more per minute. This increase in heart rate makes the body believe that it is working harder than it actually is, thus raising the basic metabolic rate for up to 24 hours. Nicotine also causes a higher concentration of sugar in the blood stream. This higher-than usual amount of sugar in the blood causes a chain reaction in the body, tricking it into thinking it has a food source, which can also raise the metabolism.
The metabolism can also be affected by the increase in adrenaline hormones released by the brain owing to nicotine. Adrenaline also increases heart rate, causing further strain on the body and increasing metabolism to make up for it. This strain, which can be equivalent to up to 90 pounds (41 kilograms) of extra body weight, is why those who habitually use nicotine products are at an increased risk for heart attacks and other cardiovascular health issues.
The sudden lack of nicotine in the body can also affect the metabolism. Once the metabolism becomes used to functioning based in part on the presence of nicotine in the body, its absence can cause the basic metabolic rate to go down to rates below what they would have been without nicotine products. This effect of nicotine on the metabolism is one of the many reasons why people may gain weight immediately following nicotine cessation.
Once a person stops smoking or dipping, it can take up to a year for the metabolism to balance and begin functioning in a normal manner. This process can be sped up by exercising, which can produce some of the same effects of nicotine on the metabolism in a much healthier way; eating frequent small and nutritious meals is also helpful. These lifestyle changes, when made in conjunction with nicotine cessation aids such as nicotine gum or lozenges, can make any weight gain negligible at best and controllable while the body gets accustomed to functioning without the effects of nicotine on the metabolism.