Not true. You can prepare a healthy meal relatively cheaply. Don't buy brand name items and you cut the price in half almost. Go to McDonald's for lunch every day and spend $3 on a burger and a drink. That's $21/week. That same person could get a loaf of bread (in this case, honey wheat) for (what I payed for it) $2.18 + tax (sales tax in my area is 10%) 1/2 lb. of roast beef: $3.00+tax and a gallon of milk: $3.66+tax
For $9.72 (including taxes) I've fed myself a better lunch for a week. Add in some applesauce for say another (Can't remember if the one on the receipt was a 4 or 6 pack so I'm just going to double it) 2x$1.84+tax. That brings up the total to $13.78, just a bit over half of the McDonald's lunch.
Gallowmere summed it up pretty good, it's about personal choices I'd say at least 95% of the time.