I'm 173cm, don't really track how much I eat, but running around 15 to 18 miles a week I hover around 75kg.
About 15 years ago I dropped from 80 to 72kg in about 6 months when I started cycling again after a long lay off, working from home I only went into the office once every 3 months or so and the first time I did I got asked if I'd been ill as I looked so different, people didn't believe me when I said, 'don't go to the chippy as much at dinnertime, don't drink as much beer, and ride your bike.'
The only time I've tracked my calories is when I tried to put a bit of weight back on as I felt a bit skinny, I went to the gym 3 times a week and followed stronglifts, along with aiming for at least 3000 calories a day, and went up to 82kg.
After I stopped the gym I levelled at 80kg, until 2 years ago when I upped the running by 25% and started walking a dog 15 miles a week, slowly dropping to 75kg without any change in diet, so that's probably my natural weight.