The 38-year-old actress shared a selfie of her lifting up her shirt to show her stomach while wearing a pair of athleisure pants and flip-flops. "I've lost 20 pounds! Many asked how? Diet and cooking out of my cook book #wholenewyou," she captioned the pic.
"I didn't feel fat, but the pressure of being on television and wanting to look sexy and beautiful took over," she writes. "I'm not proud of it. I got skinny, true, but the pills caused my heart to race, and I knew in my gut that I was hurting myself."
She adds, "What I eat and what I put into my body is extremely important to me."
See photos of Tia Mowry:
Tia Mowry through the years
Tia Mowry through the years
LOS ANGELES, CA - NOVEMBER 3: Tia Mowry attends a special screening of Open Road Films' 'Spotlight' held at the DGA Theater on November 3, 2015 in Los Angeles, California. (Photo by JB Lacroix/WireImage)
WESTWOOD, CA - NOVEMBER 01: Actress Tia Mowry and son Cree Taylor Hardrict attend the premiere of 20th Century Fox's 'The Peanuts Movie' at The Regency Village Theatre on November 1, 2015 in Westwood, California. (Photo by Alberto E. Rodriguez/Getty Images)
BEVERLY HILLS, CA - OCTOBER 05: Tia Mowry arrives at the Industry Screening Of Sony Pictures Classics' 'Truth' at Samuel Goldwyn Theater on October 5, 2015 in Beverly Hills, California. (Photo by Steve Granitz/WireImage)
NEW YORK, NY - APRIL 29: Actress Tia Mowry leaves the 'Today Show' taping at the NBC Rockefeller Center Studios on April 29, 2015 in New York City. (Photo by Ray Tamarra/GC Images)
NEW YORK, NY - APRIL 27: Actress Tia Mowry visits SiriusXM Studios on April 27, 2015 in New York City. (Photo by Monica Schipper/Getty Images)
LOS ANGELES, CA - APRIL 21: Tamera Mowry (L) and Tia Mowry sign and discuss their new book 'Twintuition' at Barnes & Noble bookstore at The Grove on April 21, 2015 in Los Angeles, California. (Photo by Araya Diaz/WireImage)
WEST HOLLYWOOD, CA - APRIL 13: Actor Cory Hardrict and actress Tia Mowry attend the premiere of 'Brotherly Love' at SilverScreen Theater at the Pacific Design Center on April 13, 2015 in West Hollywood, California. (Photo by Jason LaVeris/FilmMagic)
BEVERLY HILLS, CA - APRIL 11: Actress Tia Mowry attends the 2015 TV LAND Awards at Saban Theatre on April 11, 2015 in Beverly Hills, California. (Photo by Jason LaVeris/FilmMagic)
SANTA MONICA, CA - APRIL 4: (EXCLUSIVE COVERAGE) (L-R) Tahj Mowry, Tamera Mowry-Housley and Tia Mowry attend Tamera Mowry-Housley's baby shower at Casa Del Mar on April 4, 2015 in Santa Monica, California. (Photo by Chelsea Lauren/WireImage)
HOLLYWOOD, CA - FEBRUARY 24: Actress Tia Mowry attends the Warner Bros. Pictures' 'Focus' premiere at TCL Chinese Theatre on February 24, 2015 in Hollywood, California.(Photo by Jeffrey Mayer/WireImage)
WESTWOOD, CA - MARCH 22: Actress Tia Mowry-Hardrict arrives at Twentieth Century Fox And Dreamworks Animation's 'Home' Premiere at Regency Village Theatre on March 22, 2015 in Westwood, California. (Photo by Barry King/Getty Images)
COMPTON, CA - MARCH 07: Actress Tia Mowry-Hardrict attends Tia Mowry-Hardrict And Nickelodeon's Nick Jr 'Beyond The Backpack Partner With Compton Unified School District For Kindergarten Registration Event at McKinley Elementary School on March 7, 2015 in Compton, California. (Photo by Imeh Akpanudosen/Getty Images)
NEW YORK, NY - MARCH 16: Actress Tia Mowry discusses 'Whole New You: How Real Food Transforms Your Life, For a Healthier, More Gorgeous You' with the Build Series at Build Studio on March 16, 2017 in New York City. (Photo by Roy Rochlin/FilmMagic)
HOLLYWOOD, CA - JANUARY 03: Actress Tia Mowry-Hardrict attends Hollywood Today Live at W Hollywood on January 3, 2017 in Hollywood, California. (Photo by David Livingston/Getty Images)
CULVER CITY, CA - OCTOBER 23: Actress Tia Mowry attends the Elizabeth Glaser Pediatric AIDS Foundation's 27th annual 'A Time For Heroes' at Smashbox Studios on October 23, 2016 in Culver City, California. (Photo by Vincent Sandoval/WireImage)