Smoking, BMI, and Adipose Tissue: What Is the Relationship?

Even with a lower body mass index (BMI), patients who currently or have ever smoked have a higher risk of developing adipose tissue in and around organs than do individuals who never smoked.

“Smokers often have lower risk of obesity measured using BMI, leading to the misconception of a ‘beneficial side effect’ to smoking,” the researchers explained.

To test the supposed benefit of smoking, the researchers used computed tomography to measure subcutaneous, intramuscular, intermuscular, and visceral adipose tissue volumes in 3020 participants from the Coronary Artery Risk Development in Young Adults study. The study was initiated in 1985 and recruited participants aged 18 to 30 years from 4 centers in the US.

Overall, they found that BMI was lower among current smokers than among never-smokers. However, after adjusting for BMI and cardiovascular disease risk factors, the adjusted mean intermuscular adipose tissue (IMAT) volume was 2.66 (2.55–2.76) cm3 in current smokers (n = 524), 2.36 (2.29–2.43) cm3 in former smokers (n = 944), and 2.23 (2.18–2.29) cm3 in never smokers (n = 1,552). Further, current smokers and former smokers had lower lean muscle attenuation compared with never-smokers. Pack-years were directly associated with IMAT volume in current and former smokers, and despite having less subcutaneous adipose tissue, current smokers were found to have higher visceral/subcutaneous adipose tissue ratio than did never-smokers.

“Despite lower BMI and subcutaneous fat, smokers appear to be at risk of accumulating organ-associated fat and intramuscular fat that have been shown to increase circulating blood fats and sugar. This may, in turn, explain some of the hidden, higher risk of CVD and disability in smokers,” they concluded.

—Michael Potts

Reference:

Terry JG, Hartley KG, Steffen LM, et al. Association of smoking with abdominal adipose deposition and muscle composition in Coronary Artery Risk Development in Young Adults (CARDIA) participants at mid-life: A population-based cohort study. Published online July 21, 2020. PLOS Med. doi:10.1371/journal.pmed.1003223