I can feed my family of 5 a low-carb meal of:
1 can Spaghetti Sauce, the kind with no sugar ($.78)
2 lbs. turkey burger (this is the 30% fat kind) ($2.00)
1.5 lbs. of broccoli (1.00)
Grand total: $3.50
(And this meal generally has some left-overs.)

To feed my family the equivalent of high carb costs as follows:
1 can Spaghetti sauce (same kind) ($.78)
1 lb. spaghetti noodles ($1.00)
1 lb. turkey burger ($1.00)
1 lb. of broccoli ($.72)
Grand total: $3.50
Most people also throw in a loaf of French bread with that (yes, even very poor people) for another $1.00.

I do realize, there are those who can barely get a tummy full, but there are also a lot of people out there who use the excuse of a limited budget not to eat healthily.