Americans are increasingly eating lunch at their desks instead of strolling to neighborhood restaurants, and the trend is costing the restaurant industry billions.

NPD Group Inc. said consumers made 433 million fewer trips during lunchtime last year. The shift in American preferences cost the restaurant industry $3.2B in 2016 , the Wall Street Journal reports. Restaurant traffic was down 2% from 2015, and lunchtime traffic was the lowest its been in about 40 years.

The Journal said employees are getting into the habit of either bringing food from home for lunch or ordering out, usually so they can continue to work at their desks. The hourlong lunch is becoming a scarce luxury as employees try to squeeze the most out of their day. To cope with the shift, more restaurants are offering delivery options, focusing their efforts on smaller portions and faster service.

Even with those changes, restaurant expenses are high. As a result, experts said new concepts are being created that cater to the changing lunchtime dynamic, so as not to lose money.