Iman on How Daughter Lexi Helped Her Embrace 8-Lb. Weight Gain: 'She Said, 'Buy Bigger Pants!''

Iman's latest lesson in body positivity came from her 21-year-old daughter Alexandria Jones.

In this week's issue of PEOPLE, the Somalian supermodel and CARE global advocate gets candid about unrealistic beauty standards and how she did her part to change them with Lexi (her daughter with late husband David Bowie). "It starts with women and it starts with young girls," Iman says of body image and inclusivity.

Conscious of how her own word would affect her daughter, Iman says she "never — no matter how I felt about myself — said in front of her, 'Oh, I've put on weight'." As a result, Lexi "doesn't think about weight in terms of being an issue," she says.

Iman, who also has an older daughter Zulekha from her first marriage to Spencer Haywood, tells PEOPLE that Lexi even gave her some advice about embracing her own pandemic weight gain, however slight.

"She said to me after [the pandemic] and I put on eight pounds, I said, "I can't fit in my pants." She said, 'Buy a bigger pair,'" Iman recalls to PEOPLE.

"Problem solved," says Iman, adding that women should not make a "big issue of not fitting in skinny jeans. You're not 20 years old. Buy a size bigger. How about that?"

For more on PEOPLE's cover story with Iman and other top stories, listen below to our daily podcast on PEOPLE Every Day.

In the cover story, Iman also discusses ageism — and praises friend Sarah Jessica Parker for embracing her gray hair and the aging process.

"Everybody's commenting about how old she is. I was like, 'What do you want from her?'" Iman tells PEOPLE. "Somebody was saying it's probably more women [than men] who are [critical] and I said, 'Well, because that's how we are programed for years, that we have to look certain ways for men.'"

In a new cover story for Vogue's December issue, Parker, 56, recalled whipping the internet into a frenzy when she was photographed dining with Bravo's Andy Cohen. Critics were quick to comment on the fact that Parker embraced her gray roots, while Cohen was also sporting a head of "exquisite" gray hair (as Parker put it). "Why is it okay for him?" Parker asked about the double standard.

"There's so much misogynist chatter in response to us that would never. Happen. About. A. Man," Parker told the magazine, in defense of women.

Iman, who was married to rock legend David Bowie for over two decades, points out that in her culture, aging is an honor. "I come from Africa — one of the things that we are taught is what a privilege it is to get old," she says. "So, I have never lied about my age."