The 32-year-old actress made her comments to Health magazine. Goodwin said she considers herself to be "extremely healthy" nowadays but was overweight when she was in grade school.
"I changed my eating habits in fourth grade because I was a heavy little girl, and I was unhappy," she said. "I remember my mom making dinner for me the first night that I was on this new program, and I burst out crying because the vegetables were green, and I thought she was trying to starve me to death. I have been a member of Weight Watchers for 23 years, and I'm back on it right now."
Goodwin also praised her "Big Love" costar Jeanne Tripplehorn, saying she taught her to make the "most amazing thing in the world" - a mixture of instant oatmeal, peanut butter and jelly.
"Big Love" returns for a fifth and final season on Jan. 16, 2011.