When I saw this thread, I decided to look at running log from the one time I did it, December 2-8 2013, to remember better how it felt at the time.
Reading back on it, it was more tough mentally than physically. I was a senior in college, a month into a marathon training plan, and building up to 100 in the final weeks/days before my senior piano recital, so I was a little, but not too, stressed in addition to preparing for final exams.
At the beginning of the marathon training (Nov 11) my previous high was 74 miles, attained 3 months before during summer training for my senior XC season. Before that summer it was 50-55. During the cross season I averaged around 55, high of 62 two weeks before conference. When marathon training began (right after conference), I got weekly mileage highs 4 straight weeks: 81, 88, 94, 100. The 100 mile week went like this:
Mon - AM 6 easy, PM 5 easy
Tues - AM 4 easy, PM 11 w/5 tempo
Wed - AM 5 easy, PM 15 easy
Thurs - AM 6 easy, PM 6 easy
Fri - 14 easy
Sat - 10 easy
Sun - 18 w/10@marathon pace.
Again, mentally it was tough, not only during this week but also in the buildup; however, physically I held up well. I made no mention in my log about being hungry or tired, though I am sure I was. I ate somewhat unhealthily at college - just ate at their cafeteria and not always the healthiest stuff - but it worked, I guess.
I followed the 100 week with 92, 93, 87, before falling off a bit leading into tapering. I have only hit 90 once since then, and that was Sept. 2014; hit 80 a handful of times. 2014 was a PR year in all distances I attempted (mile, 5k, 4mile, 10k, 1/2 marathon, marathon; the high mileage base from 2013 apparently had a good long term effect. I was hit by a series of injuries in fall 2015 and have never come back to running until 2 months ago but am struggling with hip problems.
Anyway, if you really want to do 100 miles, you would probably be okay, especially if you build up at least a little bit and are smart about how you do it, following various suggestions people have already given you.