When you enter most supermarkets, the areas along the outside walls are often where you find fruits and vegetables, meats and fish, and the dairy products.
The inner aisles are filled with all the prepared and packaged goods, all the fake foods made with high-fructose corn syrup, hydrogenated vegetable oils, and genetically-modified grains - none of the the things that existed in 1776, and none of the stuff you should be eating.
Fill up your cart with as much real food as you want. You're not going to get fat by eating produce. If you have to venture into the inner aisles, do so to pick up rice, pasta, and some condiments to flavor the real food you found along the permimeter of the market.
Be sure to park your car far from the door, so you have to walk across the parking lot, and bring reusable shopping bags (they're easier to carry, hold more, don't tear, and are good for the environment).
If there's a farmers market near your home, don't hesitate to shop there first, and buy from the supermarket only those things you can't get at the farmers market. Eating local food is good for you, good for the local farmers, and good for the environment.
