How Debra Messing Lost 20 Pounds

April 23, 2014 — -- Debra Messing has never looked anything less than drop-dead gorgeous.

You would never know it, but the "Will & Grace" icon, 45, recently made an effort to eat better for her health and it's definitely paid off big time.

"About two to three years ago, I made a very, very big change the way I approach nutrition," she told ABC News. "I think it made a big difference in how I look or at least how I'm perceived to look."

Read: Debra Messing Teams With Adopt-a-Classroom

See: Debra Messing, Maria Menounos Bare All, Overcome Body Image Issues

She continued, "I lost like 20 pounds, it wasn't my intention, that wasn't why I made the change. I made the change because I was just tired all the time. For a long time, I just accepted that was the plight of a working, single mother. You're juggling everyday."

Messing admitted that she grew up eating "crappy foods."

"I grew up on fast food and candy every day," she said. "Pizza and french fries and burgers -- I love food and I've always loved food. Vegetables were not a part of my life at all"

Now, she is focused and feeling the difference from head-to-toe.

"I'm just eating really, really clean healthy foods," she said. "Obviously I knew there was an association between what I ate and whether I gained 10 pounds or lost 10 pounds, but it never really became a reality for me that it shows on the outside in your hair and skin and even the clarity of your eyes. I was just stubborn."

Messing, who just filmed a new pilot "The Mysteries of Laura," said she starts every morning with a green juice.

"[That includes] kale and spinach and celery and ginger and lemon and cucumber," she said. "At least I know I'm starting my day and getting a big shot of nutrients that I need. I start out strong ... For the pilot, I was shooting 15, 16, 17 hours everyday. I really depended on having that juice once or twice a day. It really gave me more energy. That made an obvious difference for me, in me feeling strong."

Messing spoke to ABC as part of a collaboration with Zyrtec.

"Allergies have been a lifelong struggle for me," she said. "I'm allergic to everything. I'm allergic to pollen, grass, mold, mildew and dust. You name it and I'm allergic to it."

Now with the proper help, Messing said she is grateful she can wake up in the morning without the constant fear of an allergy attack.

"I know I'm going to be okay, whether I'm going out to Central Park with my 10-year-old son to play soccer in the middle of the pollen vortex, or doing a Broadway play in a 100-year-old theater covered in dust," she added.