Trying to cut down on cigarettes? Some studies have found that people who cut back aren't doing themselves any good—they just end up sucking harder on fewer cigarettes. Researchers at Ohio State University studied how women smoked when they cut back, including racial differences in smoking habits.

What the researchers want to know: When the number of daily cigarettes smoked is restricted, do female smokers compensate by changing the way they smoke (inhaling more intensely or more frequently)? Do black and white women smoke differently?

What they did: Through local advertising, researchers recruited 25 female smokers. Thirteen of the women were black and 12 were white. They stayed in private rooms at the research clinic where researchers studied the participants over the course of six days as they changed their smoking habits: each patient was asked to smoke their usual number of cigarettes for two days, half their usual number for two days, and 167 percent of their normal number of cigarettes for two days. Participants smoked their cigarette brand of choice. Researchers measured the participants' cotinine and carbon monoxide levels before and after smoking. (Cotinine is a metabolite of nicotine scientists use to measure how much nicotine someone absorbed.)

What they found: When the participants cut down the number of cigarettes smoked, they compensated by inhaling more deeply and frequently, and smoking more of each cigarette than usual. When they smoked fewer cigarettes than usual, they had considerably more carbon monoxide in their systems per cigarette than when smoking their normal number or more cigarettes than usual. Other studies have indicated that black women smoke fewer cigarettes each day but have higher levels of cotinine in their blood, which suggests that black women might absorb more chemicals even though they smoke the same amount. And, indeed, black women in this study had higher carbon monoxide levels per cigarette than white women.

What this means to you: The idea behind smoking fewer cigarettes is to diminish the health risks of smoking. But if you compensate by smoking more efficiently, you are defeating the purpose of reducing your cigarettes.

Caveats: All the black women smoked menthol cigarettes while only one third of white women smoked menthols. There could be some unknown factor in menthol that influenced the results. The participants' menstrual cycle phase was not considered. Also, studies have shown that carbon monoxide causes less serious damage than other cigarette ingredients. However, an increase in carbon monoxide could indicate that other dangerous cigarette components increased, too.

Find out more: A support site for smokers trying to quit: www.quitnet.com

NIH resource center for smokers: http://health.nih.gov

Read the article: Ahijevych, Karen et al. "Levels of Cigarette Availability and Exposure in Black and White Women and Efficient Smokers." Pharmacology Biochemistry and Behavior. April 2004, Vol. 77, No.4, pp. 685-693.