I'm in b-school (not remotely as demanding as law school but still). I run 40 mpw (still coming back from injury.. slowly) and eat EXTREMELY healthy. And it's easy. The key is putting a little more thought/effort/diligence into grocery shopping. Plan ahead with your shopping and bring a list.
Generally, I live by the rule.. "nothing from a box" except whole wheat pasta or brown rice. Here's how to do it quick and cheap:
-Fresh fruit. Buy enough so you have 4-5 servings a day. Great way to get carbs. Great quick snack. Healthy as f***. You'll never feel so good as when you're getting all the vitamins and fiber of 4-5 pieces of fruit a day. I go for bananas, apples, oranges, grapes, cantaloupe, etc.
-Fresh veggies as snacks. I don't cook. I hate cooking or making meals or anything from a recipe. That doesn't preclude healthy eating or getting veggies though. Carrots or baby carrots, cucumber, tomatoes. Eat them with balsamic vinaigrette or hummus for a healthy snack.
-Brown rice. 10 minutes. Whole wheat pasta. 10 minutes. Easy, healthy source of carbs and fiber. Your body loves this stuff. If you have time to boil water, you have time to eat healthy.
-Low fat dairy products. Good source of calcium and protein. Low fat or fat free PLAIN yogurt. Plain is important because flavored yogurt is sugary junk that will make you feel like shit. If you can't stand the taste, add fruit or granola. I personally like the taste. Low-fat cottage cheese is another great source of calcium/protein.
-Frozen veggies. Once again, so easy and a great low calorie source of nutrients. Lots of nights I come home and make a bowl of pasta and microwave some broccoli or peas. Boom. Dinner. May be "boring" to some people but when you get used to it, it's awesome. Add a dash of soy sauce or some grated parmasean cheese for flavor. It takes 5 minutes to microwave veggies. Get some tupperware, microwave it in there, then throw whatever you don't eat into the fridge for next time.
-Other stuff that doesn't fit into the above.
Canned salmon: ready to eat, low calorie source of protein. Tasty, straight from the can, mix it in with rice or pasta or veggies.
Eggs: Good source of protein and fat, quick to prepare, get a non-stick pan and clean up is minimal.
Nuts: Almonds, walnuts. Protein, fat, good for your skin. Don't over do them.
Yams: The one thing I eat that takes some prep/cooking time. But tasty and worth it.
Beans: One of the few things I eat from the "middle aisles". They're nutrient-dense and good in moderation, but pretty high in calories. Black beans with fresh salsa is a favorite. Chick peas are tasty and kidney beans are an awesome source of iron. Good for protein.
Extra Virgin Olive Oil: easy way to add healthy fat to most foods. Good for your heart. Add a drizzle to anything.
Eat this diet and I guarantee you will feel physically amazing. Not to sound like an infomercial, but I feel 1,000% times better and have more energy eating this way than eating cereal, powerbars, peanut butter, frozen pizzas, whatever. Plus it is easy and not too expensive. Hope youre listening!