Cigarette Smoking & Abdominal
Obesity: A Meta-Analysis
Lu Shi
Jeroen van Meijgaard
Esa Eslami
UCLA School of Public Health
Department of Health Services
Research Objective
The notion “smoking as weight control” might
encourage smoking initiation among
never-smokers, discourage quitting
among current smokers, and increase
relapse among quitters who often
encounter weight gain.
This study evaluates the magnitude and
significance of the association between
cigarette smoking behavior and WHR
Method
• Database searches of MEDLINE and Google Scholar
were conducted. Citation list searches were also used.
• Studies that have tested the association between current
smoking and waist-to-hip ratio were included, while
studies that have not controlled for age, gender, and
body mass index were excluded
• Includes 83,962 people aged 18 and above, which
include different racial and ethnic groups of countries in
Europe, North America and South America.
• Data were analyzed using the SPlus/R function of MiMa
(Viechtbauer, 2006).
Principal Findings
• All 13 studies find significant and positive associations
between WHR and current cigarette smoking.
• One reported significant and positive association in its
male sub-group but not its female group, and two studies
reported a positive and significant association in their
female sub-groups but not their male sub-groups.
• Current cigarette smoking is associated with a pooled
effect size of 0.014 increase in the smoker's WHR
(p<.001).
• Gender of the study populations is not a significant
moderator for the effect size.
Conclusions
• Cigarette smoking is very significantly associated with
abdominal obesity across different country and gender
groups.
• The biological mechanism? Inconclusive yet.
(e.g., cortisol concentration, smoking’s antiestrogenic
effect, could induce a diet that leads to more visceral fat
accumulation, etc.)
• More studies are needed to examine causal
mechanisms between abdominal obesity and cigarette
smoking
Practical Implications
•
Smoking cessation interventions may find it effective to
emphasize the message that cigarette smoking could
contribute to the smoker's abdominal obesity, which:
1. does not bring the smoker an ideal body shape
2. is often a stronger predictor of health outcomes than
BMI.
•
It might also be advisable to evaluate the WHR
outcome in smoking cessation programs.
•
The message: there may or may not be a tension
between smoking intervention and obesity intervention,
depending on how we define “obesity.”
Limits and Discussions
• Not yet a very exhaustive search of the literature in that
only PubMed and Google Scholar are used. Research
engines like DOAJ should be used as well.
• Keyword search might not have captured all the studies
that have examined cigarette smoking’s effect on WHR,
particularly when the effect is insignificant.
• Shall we control for BMI or do we use BMI as a modifier
in the meta-regression?