Hi there
I too am new to low-carb but I did find all the info on the Big Mac and I decided to post it here incase you still needed it.
The whole entire Big Mac with bun and all has 50 carbs.
If you get rid of the bun that leaves 10 carbs.
To my surprise, 6 carbs of that were from the onions, so if you get it without onion we're down to 4 carbs.
2 of those are from the sauce and the rest from the meat/cheese. It shows 0 for the pickles and lettuce.
The sauce, even though only 2 carbs contains 4 different types of sugars. And then, not every McDonalds employee puts exactly the same amount of sauce on, so you could end up with more than that.
This is what I would do. I would get it without sauce, bun and onion during induction definately. They are usually more than happy to add lettuce or pickles at no extra charge in place of that or you could probably have them put a little mustard on it if you have to have something on it. Later on, when you can have more carbs I would order the sauce on the side if I have to have it, so I can control how much to use.
When you get back in your higher carb ranges I wouldn't worry about those 2 carbs too much. I may be wrong (and if anyone reading this knows I wrong please correct me) but its not like the Big Mac gets eaten every day plus there are other foods where you can easily consume a lot more carbs than you realize.
So I hope the info above helps a little.
Have a good weekend
<Annett