I've been doing that for more than five years. Not five summers: five whole years. I only very rarely eat at the office. I guarantee that your body will adjust after a little. In fact, you'll probably be surprised about how little it takes to get accustomed.

In fact, I think this is why intermittent fasting is somewhat easy to adopt: it's surprisingly fast to adapt your body to a different meal schedule, as long as you're eating as much as you need.