What about intermittent fasting with a feeding window focused on the time when you have to eat lunch with co-workers anyway? It's sustainable for a longer period of time and you can do it while working. Look into the FAST-5 diet, which is basically, train yourself to push breakfast later in the day and eat within a 5-hour window. You can exercise, which is important. Basically, you can do intermittent fasting while living a normal life, not so with water-fasting.