The warehouse workers of BJ's Wholesale Club provide millions of people with bulk breakfast cereal and toilet paper.
Now they're also providing some gold-standard data on the effects of workplace wellness programs, courtesy of a major Harvard study in the journal JAMA.
The research finds that such programs do lead more employees to exercise and watch their diets, but they don't bring short-term improvements in health.
The randomized, controlled study followed more than 30,000 employees at BJ's warehouses around the Eastern United States. A wellness program at some sites did improve health behaviors, says Dr. Zirui Song, assistant professor of health care policy and medicine at Harvard Medical School.
"However," he says, "we found the workplace wellness program did not result in significant differences in clinical measures of health like blood pressure or weight, health care spending or utilization, or employment outcomes after 18 months."
Among the measures that showed no improvement: self-reported health, sleep quality, weight, cholesterol, absenteeism and job performance.
He says the study doesn't rule out health benefits from the wellness programs, but it may be that 18 months is too early to see them — or too late, if employee health effects peter out.
Overall, he says, "I would say that these results temper some of the employer expectations of achieving large returns on investments from workplace wellness programs in the short term."
Those expectations were raised by initial research that suggested employers might gain such great benefits that investing in workplace wellness could bring a three-to-one return.
But similarly cautionary results came from an Illinois study last year that found virtually zero benefits from a workplace wellness program in its first year.
But the field of workplace wellness is still a young field, Song notes, "and this study or any study in particular is unlikely to be entirely generalizable to this industry."
Efforts to improve health in the workplace "are certainly worth more study," he says. Which types of programs "can move the dial on employee health or workplace wellness or population health are also worth more study."
Including by the authors of this new study: They'll be continuing to follow the BJ's workers to monitor longer-term outcomes.