When I was un-and-underemployed, I spent about three years living on approximately $25,000/year. I'm single, so it was just me.
It was doable, but not easy. And I live in the northeast, which, while not the most expensive part of the US, still is far from the least expensive.
I rent, and I had to move in with a roommate to save money. Nothing against the roommate; she was nice, but I prefer to live alone. That was the largest and most painful adjustment I had to make.
There was money for the rent, and utilities, and gas and food. My car was paid off.
No new clothes, except for new shoes, because the retail jobs had me in pain. Proper shoes, that cost more than a week's pay from the job, helped a lot with that. No eating out. No trips to see family--gas and tolls were too expensive. I simply did not buy anything that I did not absolutely have to. Food was healthy enough, but very plain and simple and no luxuries, like nuts or chocolate. No alcohol.
No real savings. I put at least $15.00/week in to a savings account, more when I was making more money. But the car would need new tires, or not pass inspection, or the temp jobs would dry up and rent would be due, and out it would all come.
This was pre-Obama care, so I had no health insurance. Temping and part-time jobs still don't provide that--so today I would have to add in the cost of that, which would be, I think, about $100/month. I went to a walk-in clinic once, for an abscess in my jaw that had me in crippling pain. I spent about $10/week on OTC medication for my allergies. Two teeth broke during that time and I just lived with it until I got a job again and could afford going to a dentist. (My town has a low-income dental clinic. I made $3000 too much to use it.)
The library was a life-saver. Books and the occasional DVD, and free concerts and movies.
When my cat got sick, I had to borrow money to have her put to sleep. I couldn't afford the tests to diagnose what was wrong (either cancer or some heart problem), and I couldn't let her suffer. And I couldn't get another cat until I got a job. That was a lonely two years.
One of the hardest things to deal with was that I had no guaranteed income. Hours at the part-time retail job varied from 7 to 20 hours a week. I temped a lot, but the pay varied from $10.75 to $16.00 per hour. Some assignments were for six months, some were for three days. If I wasn't working, I took whatever temp job they offered. But because my income was unstable, even when I was bringing home a decent amount every week, I had to save whatever I could, for the months when I had little temp work available. There was never a time when I could relax about money. It was a constant calculation of how much I had, how much I was making that week, how much I could spend on food and gas that week, in order to pay the rent next month.
When I finally got a job, it had been so long since I'd been in a store, other than the grocery store or drug store (or the one I worked at, where I couldn't afford to buy anything), that the first time I went to Target, it was like visiting another planet. There were so many things!
I had always been frugal, so my life didn't change drastically, except for the roommate. I think if I had a steady, regular income of the same amount, Iit would have been easier. I certainly would have worried a lot less. The source of the income probably matters, as well. I was working 2 or 3 jobs at a time, and therefore had limited time and less energy for some cost-saving measures that I had always done. If, on the other hand, I was getting a pension of $25,000 a year, and had plenty of time, I could probably cut the food bill considerably.
Renting might not be the best investment, but when the dishwasher broke, I didn't have to pay to replace it. I also didn't have to spend time or energy on lawn care, snow removal or home maintenance, so that was probably a wash.