Is walking for about 25 miles on a 1,700 calorie diet bad for my health?

I think there are faster ways to build pecs and tighten bands and burn fat, however, if this is what you want to do and you have the time and energy, I say have it. One warning I have is to make sure to eat enough and bring food and water. Walking down an old brammeled hiking path and passing out hoping for a good Samaritan who isn't scared shitless of being called a rapist for helping a passed out little girl get out of the forest of rapists.Suburban hiking pathes are always great hobo and bum spots. Nothing will happen if you hold you head up and know how to engage or ignore. Can't do that passed out or run very fast dehydrated.

no it's not

You won't succeed if you try to do this on a regular basis.

You'll need more than 1700 calories the day you walk that far.

Yes. You should be eating WAY more than 1,700 calories if you are going to be walking 25 miles every day.

Over what period of time. A few miles a day on 1700 calories is fine. 10 miles a day on 1700 calories wouldn't be.