Are you sure it's your diet? I'd investigate lack of exercise before worrying about diet.

In my experience the act of sitting in front of a computer all day just makes me feel lethargic, no matter what I eat. I went on various forms super healthy diets and none of them really changed anything. I generally felt much better when I went to the gym for 2 hours before going into work. However, I felt even better on the days I didn't go into work at all.

I can eat garbage like nachos, beer, french fries and go snowboarding all day and feel on top of the world. I determined that sitting around all day is a slow death, and my body was letting me know.