I got through med school on a similar budget.
Breakfast:
Wholewheat toast with peanut butter. Orange juice (from frozen)
Lunch: sandwich
Dinner: Budget Gourmet (when they were 99 cents on sale), macaroni and cheese in those little 3 for $1 box, turkey hot dogs.
In retrospect....not a very nutritious approach...but it seemed like the thing to do at the time.
Really, though, peanut butter is a very affordable source of calories.
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