Eat sensibly. Stick to light easily digestible foods like scrambled eggs, a slice of toast with jelly, maybe risk eating a half-order of hash browns and juice. Or, you can avoid all risk and simply order some oatmeal with fruit. Wait at least 15 minutes after eating for food to digest. Also, pedal slow for the first 15 minutes after you get back on the road.

To avoid "stiffening up" there is little you can do. Joints will do that if you rest for half-hour to an hour. However, be sure to wear a warm-up jacket and something over the legs if you will be in A/C. That should allow you to loosen up rather quickly once you get back out on the ride.