A college student on an urban campus, I cooked for myself for the past two years of school. Every week I planned what to eat for the following week, walked to the grocery store, and then carried my groceries back. The nearest store was over 1.5 miles away from my dorm during junior year, but I fortunately moved within 0.2 miles during senior year. Without a car, I had to really plan a manageable amount of groceries to buy and carry each week.
Since I was quite new to cooking, I made sure to learn about the best ways to store the perishable groceries. Keep onions and potatoes separate from each other in a cool, dry place; wipe water off of bell peppers, greens, and other produce to prevent mold in the refrigerator; buy only enough milk and yogurt for the week; and if I could buy only large packages of cheese or blueberries, then I'd be sure to set aside how much I expected to use during the next week and freeze the rest.
In the end, I think I wasted much less food than the average American college student, but unfortunately I didn't keep a waste diary. Because I had to carry all my food from the store, it was favorable to buy only what I needed, thereby reducing waste from over-purchasing. Planning my meals also meant that I made just the right amount of food for the week. And properly storing perishables meant that my hard-earned food (both in terms of a student budget and carrying it such a distance) didn't go to waste.
In stark contrast, however, some of my closest friends wasted more food than anyone else I know. With five people in their half of the duplex, it made sense for them to buy in bulk from Costco, supplemented with a few smaller items from the local grocery store. Though they shared some of these groceries, they all cooked separate meals for themselves—which quickly led to a refrigerator packed with leftovers. Sometimes those leftovers would be consumed, but other times forgotten behind all of the other items in the fridge. My friends were mostly aware of best ways to store foods, but there is only so much anyone can do with a pack of 5 heads of romaine lettuce before it spoils. I would occasionally visit on Sunday nights, when they would dump out incredible amounts (at least in my opinion) of spoiled leftovers or old produce. It frustrated me, and I would try to offer suggestions for better shelf-life or ways to prepare old-but-still-safe produce.