Full-time workers in the U.S. who are overweight or obese and have other chronic health conditions miss an estimated 450 million additional days of work each year compared with healthy workers -- resulting in an estimated cost of more than $153 billion in lost productivity annually.

These findings are based on Gallup-Healthways Well-Being Index data collected between Jan. 2 and Oct. 2, 2011. Gallup surveyed 109,875 full-time employees -- those who work at least 30 hours per week -- during this time period. The Gallup Index uses respondents' self-reports of their height and weight to calculate body mass index (BMI) scores. BMI values of 30 or higher are classified as "obese," 25.0 to 29.9 are "overweight" and 18.5 to 24.9 are "normal weight."

Chronic health conditions in this analysis include being overweight or obese; having ever been diagnosed with a heart attack, high blood pressure, high cholesterol, cancer, diabetes, asthma or depression; and recurring physical pain in the neck, back, knee or leg in the last 12 months.

Gallup calculated unhealthy days using respondents' answers to the question, "During the past 30 days, for about how many days did poor health keep you from doing your usual activities?" Full-time workers who are of normal weight and do not suffer from chronic health conditions make up 13.9 percent of the U.S. workforce and average 0.34 unhealthy days each month, or about 4 days per year. The average number of unhealthy days per month is slightly higher at 0.36 among those who are overweight or obese and do not have additional chronic health conditions.

Unhealthy days per month increase further to 1.08 for workers who are overweight or obese and have one to two additional chronic health conditions. Workers who are of an above-normal weight and have three or more chronic health conditions report a significantly higher average of 3.51 unhealthy days per month, or about 42 days per year.

The $153 billion in annual lost productivity costs linked to unhealthy workers in the United States is more than four times the cost found in the United Kingdom. The striking difference is the result of fewer unhealthy workers in the U.K.  About 14 percent of full-time U.S. workers are of a normal weight and have no chronic illness, compared with 20 percent in the U.K.  The high percentages of full-time U.S. workers who have less than ideal health are a significant drain on productivity for U.S. businesses. However, employees and employers have the opportunity to potentially increase productivity if they address the health issues that are currently plaguing the workplace.

The cost in lost productivity estimated in this analysis would increase if it included presenteeism—when employees go to work but are less productive in their jobs because of poor health or wellbeing. Including part-time employees would also add to the estimate of costs in lost productivity. Other research that has examined a broader array of factors using a somewhat different list of chronic conditions places the economic losses across the spectrum.