"There's nothing to say"
I hear this complaint from restaurants all the time and it drives me crazy. Nothing to say about your restaurant - really?
I think what happens for operators is that living it daily can make the business regular, but that's not the case to your customers - folks are fascinated with restaurants and they want to know what's going on.
There's a simple acronym you can use when thinking about your online content - ICEE - Inspire, Connect, Entertain and Educate. If you think about your posts like this, then you're going to be producing good content - whether it's for your e-newsletter, Facebook, Instagram, Twitter or elsewhere.
Some things you can do are go behind the scenes and that can be in the kitchen, behind the bar, what goes into opening up the restaurant, who are the people, what's going on. Including photos and videos as posts is an important part of that.
Then, if you were to sit down and brainstorm about what is going on at your restaurant you'd come up with things like: events, new menu items, promotions, restaurant news, kid stuff, holiday/seasonal messages (and isn't there a holiday to market around almost every month - just pull out a calendar), sports in town/region (especially if there is a big and meaningful game coming up), gift card or merchandise sales, catering & take out and also party planning.
The point is there's a lot to talk about in the restaurant business. Rather than stressing that you've got nothing to say it should be something you can have fun with as you communicate with your customers.