Is Subway necessarily lower in calories? Is Subway a good "diet-food"?
The answer is not really. If you look carefully at the nutritional information on their website you would realise that their healthiest sandwiches range from 213-320kcal (without any sauce)
That is to say that it is equivalent to one fillet-o-fish at 350kcal. (and our fav. fish burger here has already taken into account the cheese and tartar sauce in that 350kcal. )
The numbers here show that subway is only slightly lesser in calories as compared to the sinful fillet. But of course, the fillet-o-fish, being labeled as JUNK food, is fried and filled with sinful cheese and sauce, so it will make you thirsty and hungry for more carbohydrates very quickly. The subway bun on the other hand, is filled with veggie. Thus it would make you feel full for a longer span of time.