Smoking and body weight: evidence using genetic instruments

Area of Science:

• Public Health
• Epidemiology
• Genetics

Background:

• Rising obesity rates over three decades coincide with declining smoking prevalence.
• Existing research presents conflicting evidence on the relationship between smoking and body weight.
• The impact of smoking cessation on population weight remains an area of active investigation.

Purpose of the Study:

• To investigate the causal effect of smoking on body weight using a novel genetic instrumental variable approach.
• To examine how smoking's effect on body mass index (BMI) varies across different BMI levels.
• To assess the utility and challenges of genetic instruments in behavioral research.

Main Methods:

• Employed genetic instrumental variables (GIV) to identify smoking's effect on body weight.
• Analyzed data from a sample of 1057 mothers in Norway.
• Investigated heterogeneity in smoking effects across the BMI distribution.

Main Results:

• Found heterogeneous effects of cigarette smoking on BMI.
• Smoking was associated with increased BMI at low to moderate levels.
• Smoking was associated with decreased BMI at high levels.

Conclusions:

• Smoking has differential effects on body weight depending on an individual's baseline BMI.
• Genetic instrumental variable analysis offers a unique perspective on behavioral effects but requires careful instrument validation and substantial sample sizes.
• Further research is needed to fully understand the complex interplay between smoking, genetics, and obesity.