Since having a stroke over a year ago, I’ve lost close to 200 pounds. And, even though I’m considerably older than the titular Brittany in Brittany Runs a Marathon, how the world’s opinion changes — for good and bad — when you drastically change yourself is so honestly depicted here that, unless you’ve been through it, you’ll probably never understand.

Good-time girl Brittany (Jillian Bell, Rough Night) is an overweight party animal who lives primarily on Adderall, self-deprecation and random hook-ups, which, as you’d imagine, depresses the hell out of her. When a doctor advises her to lose 50 pounds, she attempts to get her shit together and starts running around New York with her recently divorced uppity neighbor and a gay dad trying to earn the respect of his son.

The tribulations that Brittany goes through to get to the marathon, from dealing with random food binges to mysterious leg pains to an Instagram roommate who tells her she be fat again soon, is an earnest account of an unhealthy person trying to change not only her outer self, but her inner self as well. That being said, it is also dramatically funny at times when it doesn’t intrinsically hurt.

Bell does a good job channeling these massive insecurities with a fully acerbic wit, but the whole romantic subplot with slacker dog-sitter Jern (Utkarsh Ambudkar, Freaks of Nature) feels a bit shoehorned in, at times threatening to turn Brittany into a stereotypical rom-com; thankfully, director Paul Downs Colaizzo always pulls back when venturing in that territory and returning the focus to Brittany and her own self-improvement.

Of course, I’ve gone through my own journey alone, so maybe I’m just bitter in that regard. —Louis Fowler