I don't know how you pack for six days, but I usually pack 3 days of food for a 4-day, into a single eBags cooler. In my first few months on the line I lost 13 pounds just by being really conscious about eating healthily and literally never eating fast food, aside from the occasional Starbucks breakfast sandwich.
Breakfast: Most hotels will provide a free breakfast. Stay away from the cereal (breakfast cereals are nothing but sugar), the waffles (duh), the eggs and bacon. Focus on oatmeal, fruit, and yogurt; as long as you avoid the sugary packaged oatmeals, a breakfast of plain oatmeal with a little honey and milk and bananas will make you feel full for a long time, and it's super-healthy. Plus, two bananas and a couple of yogurts can be your lunch. Or if you're just really hungry, toast a muffin and sure, throw some eggs and bacon in it, and there's your lunch. Warning: hotel scrambled eggs are made of some unknown substance that inevitably tastes horrific within 5 minutes of cooling down, so...
Lunch: Before heading out, I make a few Tupperware containers of a nifty chicken 'salad' that's simply the following: roasted chicken breast cut into pieces, cherry tomatoes, apple slices, baby carrots, toasted walnuts, sliced red onion pieces, and a little crumbled bleu or gorgonzola cheese. Plus poppyseed dressing (on the side, stored separately...never ever pour dressing over your salad till you're ready to eat.) Anyhow, this lunch is supremely healthy and doesn't require a microwave, so if you've got a 5-leg day with 30-minute turns, you don't have to worry about finding a crew lounge with a microwave.
Dinner: My angel of a wife pre-makes and freezes my dinners. I can fit 3 dinners and 3 of the above lunches into my cooler bag, plus a couple of cold packs. I personally detest 4-day trips, so by Day 3, having a home-cooked meal on the road is just a wonderful slice of home.
Keeping all of the above cold isn't always easy. If I'm doing a bunch of hub turns I will leave most of my food in the crew lounge freezer. If it's a 4-day that never comes back to the hub, I'll do the best I can to keep the bag out of the sun (or, if the CA has the packs set to minus bazillion degrees, right up by the rear vent on the CRJ, which keeps my bag practically frozen.) Not all hotels have in-room fridges, and even fewer have in-room freezers, so sometimes I'll ask the front desk to put my entire food bag in their staff fridge/ freezer.
For snacks I use the top pocket of the eBags to carry small chocolate pieces (not candy bars!), granola bars, etc. No matter what any label says, even the healthiest granola bars are loaded with sugar, so I eat these sparingly...but sometimes you just need some sugar to get you through the day.
Once you make the switch to eating healthily, it is incredible how your body gets used to it, and starts to reject the fatty foods you used to eat. Don't get me wrong; I still love me a medium-rare tenderloin with a side of fries and a big mashed potato, or a big, greasy, drippy burger with mushrooms, fries, blue cheese, and bacon. But I can only eat like that once a week. Any more and my body's like 'Dude, what are you doing to me?!?"