Tech startups and giants such as Google and Facebook may provide employees with all the healthful coconut water and seaweed snacks they can handle, but if their employees are reaching past the good stuff and just scarfing down corn chips, all is not well.

Studies show that 70 percent of Americans 20 and older are overweight; more than one-third (38 percent) are obese. Obesity is associated with increased absenteeism and reduced productivity while on the job. Add it all up, and obesity results in $1,429 higher annual health care costs for people who are obese, said the Centers for Disease Control and Prevention.

A growing number of companies, including Microsoft, Google and GEICO, are hiring experts to help them ensure employees are not overdoing it at the commissary.

The cafes at Microsoft, for instance, offer an array of healthy dining options, as well as a “Real Easy Wellness” food labeling system to help hungry employees spot which foods are the most nutritious.

Similarly, Google stocks its cafes and kitchens with nutritious meals that are color-coded for easy identification.

GEICO’s dietary intervention project was particularly ambitious.

Researchers with the nonprofit Physicians Committee for Responsible Medicine teamed with the insurance giant to show that office workers can lose weight, lower blood pressure and reduce absenteeism if the company provides healthy low-fat vegetarian alternatives in the company cafeteria.

“People generally want to be healthier, but sometime they don’t know where to begin,” said Dr. Neal Barnard, a Washington, D.C., physician and principal investigator of the study. “If the employer supports those healthy goals, it’s a real gift.”