Almost eveyday (bout 5 times a week) I eat a trukey sandwich for lunch consisting of 2 slices of whole wheat bread, turkey, lettuce, and a thin slice of cheese (unknown cheese) cuz thats the closest thing to a paleo food at my school cafeteria. Will that affect the Paleo diet? like will it make a HUGE difference in the diet?
It's not about gaining "weight", although that will happen on its own. It's about eliminating toxins, one of which is included in wheat.
Why do you need a sandwich? You could pack your lunch in a pyrex container and bring a fork along. Lots of options beyond sandwiches. Wouldn't you rather have a steak with a few slices of bacon on some mixed greens?
(As an aside if that cheese is "American" - that's not really cheese but rather a cheese like product made from industrial seed oils - in other words, a food-like-toxic substance.)
I haven't had any wheat in two years and feel much better for it. If you listen to authors like Dr Davis of Wheat Belly fame, he will tell you that wheat is addictive. I believe it, as I can't really stop eating it so giving it up has saved me loads of calories that weren't doing me any good. When they put that bread basket down on the table in a restaurant, I wouldn't leave any bread, even if it was horrible.
Will you gain weight eating two slices or will it adversely ruin your health? Only you will know.
If you don't want to get rid of your sandwiches, check out the WAPF diet. Essentially replace the "whole wheat" bread with "sprouted" bread and you should be set. Again with the cheese...it HIGHLY depends on what kind of cheese. Since you only put a small bit on, either a) try it without cheese or b) buy high quality hard cheese.
I'm lucky and eat Paleo because I like to be healthy, not because my body has problems with any type of food. If you want to go strict Paleo and heal any problems then you want to eliminate both bread and cheese for now. If you just want to be healthy, look for better versions of the bread, cheese etc.
try eliminating the sandwiches for 30 days (do a whole 30) then have one to see how you feel. By doing an elimination diet, and adding foods back in, you can figure out how they're really affecting you. If you notice no changes, then perhaps you don't want to be on the Paleo diet.
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