"I think my weight is my biggest lifetime struggle," the E! reality star says in a video on her blog. "My weight is always going up and down. I'm always fighting that."
Even though Kardashian, 26, says her weight is "a struggle that I think I've gotten a hold of," she worries about public opinion.
"I feel like no matter what I do, I never look good enough to everybody else," she says.
As for tackling everyone else's opinions, "Other peoples' words do come and hit you hard," says Kardashian, who is working on a new reality show which documents her life with husband Lamar Odom. "It's not the biggest thing in life, but it gets you down sometimes."