TOBACCO: SMOKING CESSATION AND WEIGHT GAIN

On the average, smokers weigh less than nonsmokers, and approximately 80 percent of smokers who quit will gain weight. The average weight gain for smokers who quit is 5 pounds compared to about 1 pound for continuing smokers over the same period, although some quitters (about 20 percent) will gain more than 10 pounds, and a smaller number (less than four percent) will gain more than 20 pounds. Women tend to gain more weight when they quit smoking than men, but the reasons for this are not known.

At least three major issues are important in the relationship between smoking cessation and weight gain. First, many smokers express fear of gaining weight as a reason for not quitting or weight gain as a reason for a relapse back to smoking. The data, however, are not clear that this is the case. Second, a number of hypotheses have been used to explain weight gain in quitters. Finally, because of smokers' stated concerns of weight gain accompanying cessation, a number of strategies to reduce or delay weight gain have been tested.

FEAR OF WEIGHT GAIN

Fear of weight gain during smoking cessation is more common in women who smoke than in men who smoke. Among current smokers who have attempted to stop smoking, women also are more likely than men to report weight gain as a withdrawal symptom in smoking cessation. Despite this, there is not a relationship between weight gain concerns and serious smoking cessation attempts for either women or men.

Research on the effects of weight gain concerns on relapse to smoking has yielded mixed results. Although many unsuccessful quitters cite weight gain as the reason for relapse, the majority of studies indicate that weight concerns prior to attempting cessation have no relationship to successful quitting. A few other studies, however, have determined a relationship between the two.

SMOKING CESSATION AND WEIGHT GAIN

It is not clear whether weight gain during cessation is temporary or permanent, although the majority of studies indicate that some weight gain (about 5 pounds) is likely to be long-term. Although the mechanisms responsible for the weight gain are not clear, a number of hypotheses have been set forward. These include a metabolic effect for smokers; this is supported by research indicating that smokers and nonsmokers have few differences in the amount of calories consumed. Another hypothesis is that smoking lowers the body's "set point" for weight and smoking cessation raises that set point to be equivalent to that of nonsmokers. A third hypothesis is based on the observation that an increase in caloric intake occurs in those who stop smoking, and increased consumption may be responsible for the weight gain. Although weight gain is likely to accompany cessation, actual weight gain during smoking cessation does not appear to be related to cessation outcomes. Nevertheless, in reaction to smokers' stated concerns about weight gain, a number of strategies to prevent or reduce weight gain during cessation have been developed.

STRATEGIES OF WEIGHT CONTROL DURING CESSATION

The focus of weight control strategies during cessation has revolved around diet, exercise, and most recently, pharmacologic agents. Weight control programs through behavioral self-management of dietary intake have been largely ineffective. In two large randomized trials of behavioral weight management during cessation, the standard care (control) groups with no weight control intervention had better cessation outcomes than the groups that received the behavioral intervention. One of the studies, however, reported that the amount of weight gained was lower for individuals receiving the dietary weight control intervention than individuals not receiving it.

In recent years, a number of research studies examining the effect of physical exercise on weight control during cessation have been conducted. The majority of these studies have been conducted with women. The largest randomized study to date found that women who participated in exercise as well as a smoking cessation program were twice as likely to be abstinent from smoking 12 months after the program than those who participated in the smoking cessation program alone. In addition, the exercise group gained considerably less weight than the nonexercise group.

Pharmacologic agents are increasingly used to prevent or delay weight gain during smoking cessation. Nicotine itself has been the focus of much pharmacologic research. The effect of various nicotine replacement delivery systems, such as nicotine polacrilex gum, the transdermal nicotine patch, nicotine nasal spray, and the nicotine inhaler, on weight gain has been assessed. Nicotine polacrilex gum has been widely studied for its weight control effects during cessation. An early review of five existing studies showed that gum users gained less weight than those on a placebo; however, the effects were small. Recent randomized studies of the effects of nicotine gum on weight gain suggest that there are no long-term effects of gum use on weight gain, and with the discontinuation of gum, there are no significant differences in weight gain between gum users and nonusers. Overall, findings are mixed in terms of weight gain during use of the other nicotine replacement products. The studies that have been conducted on the nicotine transdermal patch indicate either no effect or a delayed effect in controlling weight gain during cesssation. Similar findings have been reported for the nicotine nasal inhaler. Overall, it appears that any nicotine replacement effects on weight gain disappear after the nicotine replacement is discontinued.

Other pharmacologic agents have also been examined for their effects on weight gain during cessation. In a study of the effects of fluoxetine hydrochloride (Prozac) on weight gain during smoking, individuals on the drug gained significantly less weight than those on a placebo; however, the followup was very short (10 weeks). A study of the effects of d -fenfluramine, which is thought to suppress appetite by releasing serotonin, on weight gain during cessation suggested that d -fenfluramine did control weight over a placebo. Serious medical complications that accompany d -fenfluramine, at least when used in combination with phertermine, however, have diminished enthusiasm for this drug. A study using phenylpropanolamine, an over-the-counter weight control drug, indicated that phenylpropanolamine users gained less weight and had higher quit rates over a placebo group and a no treatment control group. A study of bupropion (Zyban) and weight gain indicated that weight gain was suppressed while on the drug, but the effect disappeared when the drug was discontinued.

SUMMARY

Smoking cessation is likely to result in some weight gain, with women gaining more weight than men. Both women and men express concern about gaining weight when quitting smoking; however, few studies have found a relationship between weight concerns and successful smoking cessation. Similarly, actual weight gain during cessation does not appear to predict relapse. Dietary programs seem to be ineffective in controlling weight gain during cessation, while exercise programs seem to have some benefit. Pharmacologic agents appear to be successful in delaying weight gain during cessation; however, after withdrawal from the drug, any significant effect on weight gain disappears.

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Beti Thompson

Revised by Scott J. Leischow