you really need to healthy.

you also need to eat a large volume of kcals ... i would say that 30 miles daily would equate to roughly 1.75-2 hrs of cycling per day ... and roughly 1100 kcals. my gf and I commute together about 1.25h/day each (so we need to come up with an extra 1200kcal/day for both of us)

personally, i would avoid anything processed like frozen pizzas, prepacked salad dressings, pop-tarts, etc ...

i find it useful to cook two large meals on the weekend ... one on Sat and one on Sun and freeze extra food away for during the week.

this weekend we made pumpkin curry with basmati rice (roughly 5L/1.5gal of curry) and about 5L/1.5gal of rice on Sat and a really nice rice/chicken/peach/peanut dish (again about 5L) on Sunday. this way we can eat really well on Sat/Sun and have roughly 8-12 high-density meals left for the week. those 8-12 meals are great for work (we work at the same place and can eat together.)

personally, i think getting enough kcals is really expensive, so i avoid powerbars/prepackaged stuff because it's too expensive and usually buy fresh produce because it's relatively inexpensive by comparison.

for example, a 5kg (11 lbs) bag of really nice Pakistani rice can be had for €15-20. 5kg of rice provides 15000 kcal and the freshly imported stuff tastes great compared to the supermarket crap!