CESSATION FROM CIGARETTE-SMOKING - CHANGES IN BODY-WEIGHT, BODY-COMPOSITION, RESTING METABOLISM, AND ENERGY-CONSUMPTION

This study examined the effect of cessation from smoking on body weight, body fat, resting metabolic rate (RMR), and caloric consumption. Twenty-six women aged 25 to 45 years (mean, 37.2 ± 4.7) who smoked 20 or more cigarettes per day for the past 5 years served as volunteers. Twelve subjects abstained from smoking for a period of 60 days (EXSMOKERS). Six stopped smoking for 30 days, then resumed the habit for an additional 30 days (RESMOKERS). Eight subjects continued to smoke for the entire 60 days (SMOKERS). Additionally, 10 women who had never smoked served as nonsmoking controls (NONSMOKERS). Body weight was recorded weekly and body fat was calculated from body density as determined by hydrostatic weighing. RMR was assessed by open-circuit spirometry. Caloric intake was obtained from 3-day food records using a computerized nutrient data base. Group means for body weight, body fat, RMR, and caloric intake were compared using a repeated measures ANOVA with a Scheffe post hoc at day 0 (baseline), day 30, and day 60 of cessation from smoking. NONSMOKERS weighed significantly (P < .05) more, but were no fatter than all smoker groups at day 0. Body weight significantly increased by 1.8 kg (EXSMOKERS) and 2.1 kg (RESMOKERS) at day 30 of cessation. By day 60 EXSMOKERS' body weight had increased an additional 1.8 kg to 61.6 ± 6.4 kg, while return to smoking (RESMOKERS) resulted in a 3.1 kg loss of body weight to 57.9 ± 7.9 kg. Body fat significantly increased from 28.4% to 30.6% by day 30 and further increased to 31.1% by day 60 for EXSMOKERS. Body fat of RESMOKERS significantly increased from 28.1% to 31.0% by day 30 of cessation and remained at that level at day 60. Smoking cessation resulted in a significant 5.7% increase in caloric intake for RESMOKERS by day 30, followed by a significant 6.9% decrease by day 60 with return to smoking. EXSMOKERS demonstrated a 3.6% increase by day 30, followed by an additional 1.8% increase by day 60, resulting in a significant 5.4% increase at day 60 when compared with baseline. RMR was significantly reduced by 16% for EXSMOKERS and by 12% for RESMOKERS at day 30. EXSMOKERS showed no further change by day 60, while RESMOKERS' RMR returned to baseline levels. No significant differences were observed for body weight, body fat, RMR, or caloric consumption for SMOKERS or NONSMOKERS. Smoking cessation leads to increased body weight due to decreases in RMR and increases in caloric intake. The resultant body weight gain is attributable to increased body fat. © 1991.