You shouldn't need 25k a year to live in a normal city. If you live in NYC, Boston or Honolulu or something, you will need that much, but if you're living in Detroit or Columbus or Nebraska or any number of other med school locations, you should be able to live off a number that is way less than 25k.
Let's say you want a 1 bedroom in a safe but QUIET (i.e. not the desired area with tons of nightlife) area in your average city. $700 a month. Your landlord pays heat and water, leaving you with just electricity to pay for. You don't run the AC and don't have TV, so you pay $80 electricity and $50 for cable internet. You shop frugally, buying only groceries that are on sale. $150 a month on groceries. You own an older car paid for in full and have $80 monthly basic insurance. You were wise and bought a reliable car with minimum repairs, say you spend $500 a year on those or $41 monthly. It gets 28 MPG. You drive 100 miles a week. Gas is $3 a gallon. You spend $40 monthly on gas. You're lonely in medical school so you buy a cat, spending about $25 a month on food and litter, plus a $100 yearly checkup or $9 more dollars a month. You spend around $50 on miscellaneous household items - cleaning supplies, shampoo, conditioner, etc...I'm a female with a hair, skincare and makeup regimen and it only runs me about $15/month. I take a multi and fish oil and that's only another $10 a month.
$1144 total = $13728 a year. Bump it up to 15k for fun, since the tires will need replacing on that car, and you might want to go see a movie once in a rare while.