Pre-cut fruit, bagged salad mixes, shredded cheese and marinated meats save time, and that convenience usually shows up in the price. Each one may only cost a little more than its whole counterpart, but across a weekly shop the difference can become meaningful.

That doesn't mean convenience items are always a bad choice. If a bag of pre-washed greens is the difference between eating a salad and ordering takeout, it may be worth it. The key is to decide on purpose rather than reaching for the prepped version out of habit.

If you want to cut back, pick one or two items to prepare yourself. Shredding a block of cheese, chopping a whole melon or washing a head of lettuce takes only a few minutes. Doing the prep right after you get home, while you're already in the kitchen, can make it feel less like a chore later in the week.