Jazmin Biltmore is a smart-mouthed, frustrated, plus-sized, aspiring fashion designer who is obsessed with her weight and struggles to find love and acceptance in a world full of "hot-bodied babes".

The story follows Jazmin, her best friend Stacy and her cousin Mia. Jazmin has always been overweight, even as a child, in comparison to her skinny, popular cousin Mia.

Jazmin uses a lot of diet pills, as it is her dream that she will eventually be a size 5. She ends up winning a trip to Palm Springs for a weekend at a posh five-star hotel.

Her friend Stacy and herself, find the first day at the spa somewhat embarrassing, as neither hotel robes will fit due to the fact that both women are plus sized, the massage table is quite small for their curvaceous figures, and they finally leave in frustration, joining Mia at the hotel pool, where the latter is ogling a Nigerian man swimming in the pool. He comes out and greets the ladies, introducing himself as Tunde saying hello to a stunned and enraptured Jazmin who is too distracted to remember her own name. His friends also join him by the pool and find that Jazmin and her friend Stacy are beautiful, however they feel that Mia is too skinny and they wonder if she is sick. One of Tunde's friends comments on how Mia reminds him of a matchstick. He and his friends invite them out, saying he has never seen such beautiful women in America.

All three women go on a date with Tunde (the Nigerian swimmer and Jazmin's new love interest) and his friends to a traditional Nigerian party, where Mia is told she needs to eat more and get over her emaciated frame. She storms out in anger because everyone there is embracing being big and beautiful. Then there is more of Jazmin's infatuation with Tunde, and shy and reserved Stacey being hit on by Tunde's friend Akibo, who pretty soon is more in carnal lust than love. Mia is frustrated because her cousin and her friend have both snagged rich Nigerian doctors and she is lonely.

Tunde treats Jazmin with the utmost respect, tells her she is beautiful and should never try to change herself to please other people. She comments on how she will eventually get down to a size 5, which Tunde comments that with her body structure, she can never be a size 5. He tells her she is a thick madame and should embrace that. She attempts to embrace that concept. She pampers herself with a massage, a manicure, as well as an avocado facial, and even indulging in cookies. That night, she goes down to dinner in an evening gown to have dinner by herself because Tunde is meeting with the president of a medical corporation. As she is preparing her all-you-can-eat buffet meal, she walks into the dining room to see Tunde sitting with a thin blond woman. She confronts him about cheating on her, but he informs her that the blond woman is actually the president of the medical corporation that he told her about. Realizing her mistake, she immediately is embarrassed and runs out of the restaurant. She leaves Tunde, has the girls leave the hotel and goes back home to her dull, boring, dreary life as a saleswoman in a Bloomingfelds. She has a breakdown and throws away all her diet pills, size 5 clothing and literally spring-cleans her room and learns what Tunde told her about loving herself and embraces being large.

Back at work at the boutique (which seems to only cater to slim women), three plus-sized women come in and demand some assistance in the plus-size section. Jazmin goes over to help, and tells them the only person who can actually help is her stuck-up manager. Her friend Ramon hands over her portfolio. Jazmin is a very talented designer but was told by her manager that her designs are too amateur for the store designer and boss to be interested in it.

She sideswipes her manager, goes up to her boss who is helping the ladies, and her boss comments on her dress which she says is her "own design". The boss leads her away for a talk.

Jazmin's career blossoms from a section in the store to a store of her own, and finally her Thick Madame clothing line goes worldwide. She holds a fashion show, having all plus-sized models including the now more confident Stacy to full-figured women of the world. PHAT stands for 'Pretty Hot and Thick'.

One year later, she decides to travel to Nigeria to apologize to the man she realizes she loves. As she and her friends get there, a woman opens up the door holding a baby. Jazmin asks if she is Tunde's wife and the woman shakes her head yes. The girls believe that Tunde has ended up marrying since they have been apart and has the girls go to the taxi because she does not like to be rejected with an audience. Tunde comes to the door and tells Jazmin that the girl is a maid in the house and that Tunde, being a gynecologist had delivered the baby for her, along with the fact that the maid doesn't understand English. Tunde ends up telling her he loved her all along. They kiss, and he promises to handle "all of her". Mia and Stacy reunite with their partners as well, and the new lovebirds Jazmin and Tunde sit down to dinner with Tunde's family. Thin Mia starts to pile loads of food on her plate stating that she wants to bulk up so she can find a rich Nigerian doctor as well, since in Nigeria, they see that the bigger you are, the richer you are.

The film ends with Jazmin and Tunde in bed having sex.