Could the obesity epidemic be due to smoking cessation? The Tromsø survey 1994-2016.

BMI has increased in men and women. Those who quit smoking are most susceptible to weight gain and should be targeted by health professionals and in public health interventions.

Background: The widespread increase in overweight and obesity in Norway coincides with a substantial cigarette smoking decline. Many ex-smokers report unwanted weight gain following smoking cessation. Can the population overweight/obesity epidemic be partly attributed to smoking cessation?

Methods: Data were collected from the Tromsø Study among 10,945 women and men aged 25-54 years who participated in the 1994-95 survey (attendance 72%) and then 22 years later (attendance 65%). We studied changes in mean body mass index (BMI, kg/m2) and weight in subgroups by self-reported cigarette smoking status, 10-year age groups and gender. We included subjects with smoking habits qualifying for the following sub-groups: Smoker (persistent daily smoker), Quitter (daily smoker in the first, but not in the second survey), Ex-smoker (non-smoker in both surveys who reported being a previous smoker), Never-smoker (non-smoker in both surveys who never smoked daily).

Results: Smoking prevalence decreased from 36% to 15% between 1994 and 2016. BMI increased in all subgroups (p<0.001); higher in quitters than in persistent smokers and non-smokers. BMI increased more in women than in men, except among persistent smokers (p=0.06). BMI increase was substantial among the youngest, exemplified by mean (SD) increase of 4.5 (3.6) BMI units in women and 4.2 (2.8) BMI units in men aged 25-34 years who quit smoking between surveys. This is equivalent to a weight gain of 12.2 (10.2) kilograms in women and 13.3 (9.2) kilograms in men.

Conclusions: Over 22 years, mean BMI increased considerably in men and women aged 25-54 years, regardless of smoking status. Weight gain was most prominent among quitters and the youngest. Public health interventions should be targeted at weight loss and weight maintenance, particularly among those who quit smoking.