When HR asks about your health

(Money Magazine) -- Don't be surprised if, as open enrollment approaches, your HR department asks you to fill out an online questionnaire covering everything from how often you hit the gym to how often you feel sad.

These health risk assessments, as they're known, are increasingly common. Half of employers surveyed by Aon Consulting use them, and 20% more plan to.

The data are usually collected by an outside company, not your actual boss. But employers hope that having someone identify their workers' health issues early -- and developing a plan to help -- will lower their insurance costs. Many firms offer financial incentives for filling out the forms. But is there a risk to sharing such personal info? Here's what to know.

What surveys can ask. The questionnaires typically ask about health habits -- Do you smoke? Do you drink? -- as well as your cholesterol levels, blood pressure, and weight. Increasingly the surveys also try to assess your motivation to change your behavior.

What you may not see: questions about family history. Many employers are steering clear of them since the passage of a law to prohibit discrimination based on genetics, says Kathy Harte of Hewitt Associates, a human resources consulting firm.

What the implications are. If you've noted that you're motivated to try living a healthier lifestyle, expect to be fast-tracked into wellness programs, such as classes to help you quit smoking, say.

This year many companies are upping the ante, tying incentives to participation in wellness programs rather than just paying you to fill out the forms. Others have even offered lowered insurance premiums to employees who don't light up or at least try a program to stop smoking.

A few companies have denied health insurance to workers who don't participate. The legality of that isn't settled, but for now you have little recourse, says employment-benefits attorney Maureen Maly.

Who can see your answers. In some (but not all) cases, it could be illegal for the company that collects your info to share it with your employer. Experts say it's unlikely anyway -- people would soon stop filling out questionnaires if they weren't kept private.

So you need not lose sleep worrying that a manager will find out how many drinks you have per week, says Lewis Maltby of the National Workrights Institute.

Not convinced? Maybe you think you'll fudge the truth? Don't. That's fraud, and could be grounds for dismissal.

In most cases you don't stand to lose anything by completing the survey honestly. And it may just direct you toward help you need.