Food delivery is becoming as competitive as the restaurant industry itself.

Not taking advantage of the trend, though, is the least advantageous option for operators, said John Barker, president and CEO of the Ohio Restaurant Association.

The association and Cleveland Research Co. conducted a study that showed 40 percent of respondents now offer small-order deliveries through such services as UberEATS Amazon Restaurants, DoorDash, Grubhub and Postmates.

The association's survey included responses from 85 restaurateurs throughout the state.

Millennials and members of Generation Z -- often defined as those born from the mid-1990s to the mid-2000s -- are driving the trend, which means restaurants need to get on board before carryout customers all but disappear, Barker said.

"You're going to be in a tough spot, if not now, in the very near future," he said.

The model for customers, Barker said, is efficient, requiring all but a few keystrokes on a smartphone.

It's not surprising, giving the busy lifestyle habits of younger diners who value convenience, Barker said.

Restaurants benefit in many ways, as well. Moving more product is the most obvious, Barker said. Also, there is no additional cost, perhaps other than ordering more supplies, and it creates greater efficiency in the kitchen, he said.

Survey respondents said delivery is providing 2.9 percent in incremental sales, with slightly lower margins than in-restaurant sales. Twenty percent more respondents plan to add delivery in the next five years, the survey said.

In some cases, adding delivery services might not seem like the best option for restaurants, particularly if the food doesn't travel well, Barker said.

"There's a breaking point for everybody," he said.

For example, delivery isn't offered by the Refectory Restaurant & Bistro, the upscale French restaurant in northwest Columbus.

Owner Kamal Boulos said only in limited circumstances would the restaurant pack a to-go order. In those cases, customers are provided with specific instructions about reheating and plating, Boulos said.

The food is part of the dining experience, he said, and plate presentation is an important aspect of guest service.

"If you come in and say, 'I want to order some carryout,' we don't feel our food presents itself well in that way," Boulos said.