haha- i fit this description! I am 31, and shop at whole foods once a week (I wish we had a convenient TJ's!).

at whole foods, you would peek in my cart and think i eat nothing but packaged foods, but really they are specialty products:
packets of seaweeds snacks
packets of crunchmame (roasted edmame)
packets of carrots and ranch dip to go
turkey jerky
quest bars for races
etc.....

BUT, this gives an inaccurate picture- i also shop at Giant once a week, and there i get the bulk of groceries:
lettuce, bell peppers, grape tomatoes, cucumber, spinach or broccoli or asparagus or shredded cabbage slaw
chicken breasts
eggs
cheeses
greek yogurt
pumpkin seeds
coconut milk
etc......

So maybe there are lots of other 30 somethings who only go to TJ's or WF's for "treats"?