Obesity adds more to health care costs than smoking, study suggests

James P. Moriarty, MSc, and colleagues of the Mayo Clinic, Rochester, Minn., analyzed the incremental (additional) costs of smoking and obesity among more than 30,000 Mayo Clinic employees and retirees. All had continuous health insurance coverage between 2001 and 2007.

Both obesity and smoking were associated with excess costs for health care. Compared to nonsmokers, average health costs were $1,275 higher for smokers. The incremental costs associated with obesity were even higher: $1,850 more than for normal-weight individuals. For those with morbid obesity, the excess costs were up to $5,500 per year.

The additional costs associated with obesity appeared lower after adjustment for other accompanying health problems (comorbidity). "This may lead to underestimation of the true incremental costs, since obesity is a risk factor for developing chronic conditions," Moriarty and colleagues write.

Smoking and obesity place a growing strain on an already stretched healthcare system. Employers are evaluating wellness programs -- such as quit-smoking and fitness programs -- in an attempt to lower costs by reducing health risk factors.

Moriarty and coauthors conclude, "Simultaneous estimates of incremental costs of smoking and obesity show that these factors appear to act as independent multiplicative factors." Their study provides new insights into the long-term costs of obesity and smoking, showing that both risk factors lead to persistently higher health costs throughout a seven-year follow-up period.