As odd as it seems, Breakfast can be extremely important especially too a Scientist. The main reason is that eating correctly in the morning prior to work or study aids in making sure that your brain has the capacity to function and that you aren't light headed. (You'd be surprised the number of students that can find themselves in the Medical room from not eating sufficiently, especially if they are doing a long day (10+ hours).
What to eat of course is entirely up to you and the budget you have. Some cereals are fortified in vitamins and minerals and could really be placed up there with taking multivitamin tablets (One of the reasons that Denmark banned such cereals from their shelves). Fibre is obviously filling, Milk provides Calcium (amongst other chemicals) and drinking orange Juice or eating grapefruit's gives Vitamin C.
There is a hypothesis that perhaps we eat in quantity the wrong way around. Currently those that eat 3 meals a day will eat a little in the morning, more at lunchtime and even more by dinnertime. However since we tend to sleep after the larger meal it means that the food we eat doesn't burn off, instead it becomes fat. So it's possible that having a large meal in the morning, the normal sized lunch then a small dinner will actually mean you have a chance to burn off your meals and not become overweight.
That of course has little to do with Scientists and what they eat but it's Scientific eating.