Spending less on food

I keep reading these stories about families completing their food shopping for mere dollars each month. They clip a lot of coupons and take advantage of sales but I wonder what their diet really consists of. I can't imagine there being a ton of coupons for fresh fruits or vegetables. Sometimes there are sales on bananas or apples when they are in season but there isn't a whole lot of fresh produce on sale during the winter months. Are they living off of Hungry Man dinners or something? Does anyone out there have experience saving tons of money on food with coupons or whatever?