How much weight can a 350 pound woman lose in a month on the subway diet?

It's a bit hard to say, basically because there are so many things that contribute to weight loss. For example age, height, daily activity level and so on.

The basic thing is to find out how many calories you can eat in a day without inhibiting weight loss. There are plenty of calorie calculators available on the internet, for example freedieting.com (you can also find many more useful tools for weight loss in here).

Long term weight loss isn't about dieting and that's why it's better to try to change eating habits. This will not only make weight loss safer (because you're not as likely to become deficient in vital minerals and vitamins) but it will also keep the weight off in the future, countering the Yo-Yo-diet effect.

But, I'd say that a 350 pound woman can easily lose about -0,5kg in a week following a subway diet (consisting of 2 main meals of a 30cm long sub and a breakfast of a 15cm sub). However, it's good to include some fresh vegetables and fruits into your diet and try to keep on the lower calorie Sandwiches they have on their menu (not going crazy with subway triple cheese club sandwiches).

The best advise for someone trying to lose weight: eat more vegetables and low-carbohydrate fruits such as Apples. They contain fibre and will make you feel full without affecting your days overall calories that much.

And from my personal point of view, it's wiser to spend your calories on a healthy meal made from fresh produce and quality protein with complex carbohydrate than to waste it on a nutritionally deficit sandwich.