The singer and actress is a spokesperson for Weight Watchers and has famously battled with her weight in the past after having two pregnancies in quick succession.
But penning a column for Glamour, the star, 34, said Eric's "unconditional love" had made her feel stronger and happier than ever.
As part of her advice for newlyweds, she said: "Let him love all of you."
"Eric has seen me at every size, and he loves me no matter what. When I got pregnant with Ace four months after having Maxwell, I was nervous about starting over again," she wrote.
"I had come so far in learning how to balance my career, family life, and hormones, and starting over again felt overwhelming. Eric was so supportive and challenged me to accept my insecurities and focus on what truly matters.
"I feel stronger than ever, and Eric's unconditional love has been a reminder of the love I should give myself."
Jessica and Eric became engaged in November 2010 but their wedding plans were postponed until this summer because of Jessica's two pregnancies. She gave birth to daughter Maxwell in 2012 and son Ace followed the next year.
Joking in the past about wedding dates, she said: "We've had two different wedding dates, but he keeps knocking me up! We're doing it very backwards, I know... I don't know, I'll just keep my legs crossed, I guess, this time."
Jessica and Eric finally married on 5 July at the San Ysidro Ranch in Santa Barbara, California.
In a statement, they said: "We are overwhelmed with complete happiness and love having made our eternal commitment. To say 'I do' in front of family, friends and, most importantly, our children has been the happiest moment of our lives."
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