Do I need to be aware of my diet?
General answer to: 'Do I have to be more aware of what I am eating or is it just fine for me to eat whatever I want...?' I'm pretty sure a doctor or nutritionist would tell you that you should eat a balanced diet, not one that is high in calories sugar and fat. I'm also sure a lot of people in this community will tell you that diet gets more important an you get older and a more sedentary lifestyle is forced on you (sitting at a desk 8+ hours a day).

If you are only doing two 5km rides a day you don't need a special diet - just a reasonably healthy one will be fine.