I think the added costs will vary depending on your circumstances and what you ate prior.

It's a bit of an added cost for me because I have a family of 4. I am the only LC eater in the household, but during the year I've been eating this way I've changed some of my family's eating habits as well, which has increased the cost quite a bit. Prior to my diet change, I bought flour and sugar by the 25-pound bag in bulk and made most of our baked goods from scratch exceptionally cheap. I regularly got yogurts, pastas, breakfast cereals, canned vegetables and other pantry staples for 80-90% off by combining coupons with sales. My freezer(s) used to be full of breaded chicken and pre-formed burger patties by the caseload. I didn't buy a lot of chips - I opted to make things like Chex mix out of the cereals I picked up for .75/box. When we wanted chips, I would fry up corn tortillas that I'd picked up 100-$<$2, slice them into triangles and deep fry them in vegetable oil that I picked up real cheap.

I used to spend $50/week on groceries for all 4 of us. Real food costs much more! I now spend 3x that most weeks. Of course I know it's worth it and try to buy in bulk as much as possible. We just ran into a few weeks of impossible circumstances that left us broke. Ahhh, life.