I felt super drained sticking to the 8 hour work stretch. I dont prefer morning because it makes the matter worse. so I typically go after work but I feel like working out in the middle of day may make me more productive in the afternoon
I have been training during lunch time for 6 years now (the start of my professional life) Before lunch is obviously better than after regarding your comfort and risk of regurgitating food.
Energy levels will vary depending on the type of workout you do. Light workouts will most certainly raise your awareness while hard workouts would decrease the energy you have for your work. From my experience, this is manageable.
Regarding diet aspect, it does not matter much when you train. Digestion takes a while and if you eat something regularly (morning, mid-morning, ...) you probably always have something digesting in your body while training and therefore energy available. So taking this into account is not relevant.