The effects of nicotine chewing gum and cigarettes on resting energy expenditure (REE) were evaluated. Twenty smoking women participated in nicotine gum and smoking administration, after which their REEs were measured. Results indicate an acute increase in REE for both nicotine gum and cigarettes. Metabolic rates for nicotine gum slowly returned to baseline, whereas rates for cigarettes quickly dropped and fell significantly below baseline. Thus, the metabolic effect of nicotine gum was greater than the effect of smoking.