updated 05/30/2014 AT 5:00 PM ET
•originally published 06/01/2014 AT 8:00 AM ET
“I miss everything,” she told PEOPLE at the Joyful Revolution Gala in N.Y.C. on Thursday.
“I loved burgers and fries and pizzas – the greasiest food. Literally if I could, I would subsist on all of that.”
The former Will & Grace and Smash star, who’s working on a new NBC show titled The Mysteries of Laura, says that her new job is helping her to avoid the lure of McDonald’s and Burger King.
“Unfortunately, working 17 hours a day, you can’t subsist [on that] and be a good employee,” the 45-year-old says, while also admitting, “I have fond memories of them.”
Her new diet – which includes a green shake in the morning that contains kale, spinach, celery and cucumber – is focused on “eating really, really well.”
“It’s really just about trying to stay disciplined, which has been a problem for me in the past, but so far so good,” she says.
Messing, who has a son, Roman, 10, tells PEOPLE that she doesn’t exercise regularly, but maintaining her “clean” diet has given her more energy.
“That was the goal from the beginning,” she admits. “It was to try to figure out how to be a working mom and to do everything that a working mom has to do in a day and to do it with energy and the optimism and the focus it needs. I just was tired of being tired.”
Reporting by LORINA LANA