• !! The only “healthy” thing at subway are the raw vegetables. Everything is as unhealthy as other fast food restaurants.
• dressing: a tbsp can add 100 cal. Fat-free honey mustard is lowest at 30 cal/tbsp
• cheese — American is lower at 40 cal/triangle. Best to add no cheese whatsoever
• veggie delite is the lightest version listed at 460 cal/foot, on 9-grain wheat bread without cheese
• tuna sandwich is “average” at 960 cal/foot, without cheese. I eat this flavor most often, and in a day I easily top 1000 cal

Source: https://www.livestrong.com/article/302587-calories-in-a-subway-tuna-sub/