‘Swan’ strong

After: 123 pounds (Caitlin Thorne Hersey)

Much like Nina — Natalie Portman’s psycho dancer in “Black Swan” — I want to be perfect. Not for any public pirouetting or a star turn in an Oscar-nominated film, but to walk the rose-petal strewn carpet at my upcoming wedding.

Portman rose at 5 a.m., worked out five to eight hours a day and lost 20 pounds over six months on a 1,200-calorie-per-day vegan diet — plus she learned to dance in toe shoes.

For my own starring role, I devised a four-week “Black Swan” diet/workout regime practical enough for a New Yorker with a full-time job. I wanted to lose 5 pounds and tone up in time to look picture-perfect in my strapless wedding gown.

‘BLACK SWAN’ SPURS SALES OF BALLET CHIC ITEMS

Thankfully, I never suffered pure madness like Nina did, but I did experience my own traumas — including a self-inflicted gym injury, being labeled a “diva” by my trainer and feeling decidedly over the hill in ballet class.

Already a vegetarian, I turned to Lose It!, an iPhone/Web application (loseit.com), to track 1,200 calories per day. The calorie limit wasn’t too difficult, but I faced (and lost) a few battles — a tasting with our caterer, a sampling of wedding wines and a pal’s birthday celebration.

My plan was to get in two hours of exercise a day — with a mix of ballet classes, swimming (Portman did a mile a day), circuit training and whatever extra cardio I could manage. I never did rise at 5 a.m. like Portman did, but I did squeeze in one long and one short workout on most days — perhaps a ballet class at night and a 20-minute cycling workout at lunch or before work. Here’s what my schedule looked like:

At the barre

Returning to ballet after 30 years (I took lessons from kindergarten through high school) was a challenge. It gave me comfort that women still wear plastic pants that look like Hefty trash bags to warm up their muscles. And while my old foot injuries returned and I started wrapping and icing my feet again, they were never as banged up as Portman’s were.

At my very first day back — a beginner’s class at Broadway Dance Center — the teacher gently suggested I let a “more secure” student stand in front of me during the floor combos. That kind of stung. Another class I rushed into turned out to be for intermediate level students, which I didn’t realize until double pirouettes were called for — and it didn’t help my self-esteem that one young dancer looked like Scarlett Johansson.

I most enjoyed a BDC beginner class taught by a delightful old Russian man, Andrey Silantyev, who emphasized classic barre and floor work. I got to ballet class two or three times a week, sometimes getting home at 10 p.m. — and then training at the gym at 9 the following morning.

Of the three schools I tried, the adult classes at the Joffrey Ballet School downtown were better suited to us dancers who weren’t looking to add ballet to a theatrical résumé, but just looking to stay in shape (and those classes included sit-ups!).

Training days

I did strength-training twice a week with my enthusiastic, tough-love trainer Sebastian Morel-Ferreira at New York Sports Club. He dubbed me “Diva” early on because of my chronic tardiness, and one time I got so stressed about being “Black Swan”-worthy that during shoulder lifts, I hit my nose with a weight bar and burst into tears. It was my finest Natalie Portman moment — and Sebastian and I kept working out.

I hit the pools at NYSC (closer to work) and at Equinox (closer to home). A half-mile in laps took me 35 minutes. Even though I entertained myself by swimming to old Vampire Weekend, Zutons and Franz Ferdinand on my waterproof MP3 player, I never made it to a mile.

The results

Overall, I managed to work out one to two hours per day about six days a week, and after four weeks, my hard worked paid off. I lost 5 pounds (to weigh 123) and two inches each off my hips, waist and stomach — plus an inch off each leg!

While I was inspired by Portman’s perseverance, I didn’t always manage to follow my own regimen. I’ll never be able to pirouette like the “Black Swan,” but I can’t wait for the first dance at my wedding, and I look more buff for it.

‘Black Swan’ diet

Here’s what 1,200 calories per day looks like (using Lose It! calorie counts)