People need to stop being scared of their food.
A fully loaded subway sub is probably at the maximum, 1400 calories... (footlong) spread that out throughout the day and supplement where you can. Hell, I know 123 pound women that consume 2300-2500 calories a day and they're still extremely fit.
As for McDonalds, I think their food is complete garbage and if you're aiming to achieve optimal protein %, I would steer clear from it. If you're just in the area of losing weight, you can still do so with McDonalds. When everyone preaches Calories in Vs Calories Out it is true.
If you're gaining weight on a calorie deficit, you're just counting your calories wrong. (or medication, thyroid, w/e medical problem.)