A lingering question nags the workplace wellness industry.

Corporate wellness programs, which began in the 1970s, mushroomed after the 2010 passage of the Affordable Care Act, also known as Obamacare. The law offered companies incentives to embrace participatory wellness and prevention programs. In theory, companies could reduce their health care insurance costs by detecting or preventing serious disease sooner and adopting a culture of health in their employee population.

But after billions of dollars have been spent on tests, screenings and wellness promotions, the central question remains: Do wellness programs work?

The growing army of wellness consultants, vendors and screening firms suggests they do. They offer studies backing their claims that wellness programs save or make employers money and improve employee health outcomes. Business health groups generally view wellness programs as solid investments in improving employee health and restraining health care costs. Some wellness industry leaders boast of a $1 to $3 return on investment.

But is there objective evidence to support the validity of those claims?

Critics slam the industry, citing flawed studies and weak evidence propping up failing wellness programs that waste employer dollars.

In surveys, most companies employing more than 50 say they offer wellness programs, with benefits ranging from flu shots and health screenings for diabetes and prostate cancer to gym memberships, smoking cessation and weight-loss programs, disease management and personal health coaching.

Corporate wellness programs are becoming big business. A study from the RAND Corp. estimated that companies spent $6 billion on wellness in 2013. Industry experts said that figure now could exceed $8 billion.

Larry Boress, president of the Chicago-based Midwest Business Group on Health, said employers can reduce health care costs by helping employees identify their risks and understand and treat their conditions.

“Treating diabetes can be incredibly expensive, but someone who understands their condition and knows what to do can be less costly,” Boress said.

Boress conceded there are ineffective wellness programs.

“The Validation Institute and RAND pointed out that certain wellness approaches don't have a high-dollar return,” he said. “We've learned that ROI is not the correct measurement approach. Based on research and experience, the value of investment is a better approach. Some initiatives reduce costs in the short term, but there are lagging indicators that you won't see a difference for three to five years.”

LuAnn Heinen, a vice president of corporate wellness initiatives for the Washington-based National Business Group on Health, said large employers are evolving toward a “well-being approach” that includes “various engagement strategies, technologies and behavior modification. Sophisticated companies are thinking beyond physical health to issues of emotional and mental health, financial security, social connectedness and job satisfaction. The well-being approach is more personalized.”

Ron Goetzel, senior scientist and director of the Institute for Health and Productivity Studies at Johns Hopkins University, said that while most companies claim to offer wellness services, a 2004 Kaiser study found far fewer actually deliver comprehensive wellness programs.

“Many just offer flu shots or something fairly artificial,” Goetzel said. “Only about 7 percent had comprehensive wellness programs.”

So Goetzel, who also serves as vice president of consulting and applied research for Truveen Health Analytics, understands that not all wellness programs are created equal. He said the good ones demonstrate a culture of health validated by the U.S. Centers for Disease Control and Prevention and several Harvard University studies.

“They concluded that those programs have a positive impact on health behaviors and financial outcomes and that, done right, can save money. You're not going to see overnight changes,” he said. “It may take two to three years to improve population health. But if you can get 1 to 2 percent improvement in each of those areas … you'd see reduced ER and hospital visits and reduced absenteeism.”

He said it's unfair to tar an entire industry based on a few ineffective programs.

“That's putting everyone in the same bucket. You can always find issues with research. Most of these critics don't do research but just throw stones. They have not shown any alternatives that work any better. But the assertion that wellness doesn't work is false,” Goetzel said.

Al Lewis, a Boston attorney and former Harvard University economics lecturer, is a leading wellness critic. Lewis, who co-authored a book attacking the industry and the data supporting it, said his primary complaint is that wellness doesn't work.

He said wellness programs — particularly the “pry, poke, prod and punish” variety — hurt consumers and waste millions of corporate dollars. He said that because employees are sometimes subjected to discredited health screenings, which could result in false positives leading to invasive tests like cancer biopsies and unnecessary exposure to radiation, some wellness programs may cause harm.

Lewis said wellness industry vendors boast of “mathematically impossible results” of 3-to-1 returns on investment and health care cost savings through studies that seldom withstand real scientific rigor and are later discredited.

“It's not just the patient harms and the phony cost savings,” he said. “There's no regulation in this industry. Vendors can sell all the health screenings they can get employers to buy, including charging for tests deemed ineffective.”

Lewis isn't completely opposed to corporations helping their employees to improve their health.

“Disease management actually saves money,” he said. “At least disease management breaks even or better. When you add wellness programs, they lose money.”

Dr. Soeren Mattke, a senior scientist and managing director of RAND Health Advisory Services, agreed that helping employees manage their chronic conditions improves their health and reduces health care costs.

“But primary prevention — encouraging people to avoid obesity and chronic disease by exercising and leading healthier lifestyles — doesn't seem to lower costs,” Mattke said.

He said program benefits often are tied to hefty incentives requiring enrolled employees to lose weight or else pay stiff penalties.

“Those programs are not particularly effective, and many are not voluntary,” he said. “Often these purported savings are achieved through smoke and mirrors.”

He said many of the studies the wellness industry relies upon have serious methodological flaws and are typically conducted by wellness vendors. Nonetheless, Mattke said he believes the wellness industry will continue to thrive.

“There will always be a few employees who like these programs and get angry if they're taken away,” he said. “Once you offer something, it's not easy to walk it back.”

Mark Taylor is a freelancer.