Anderson, who has famously whipped Madonna and Gwyneth Paltrow into shape, revealed to DuJour magazine that she has lost nearly all her baby weight just six weeks after giving birth to her daughter Penelope in May.
"A lot of women use pregnancy as an excuse to let their bodies go, and that's the worst thing," Anderson told the magazine for its September issue.
"I've seen so many women who come to me right after [having children] with disaster bodies that have gone through hell, or they come to me years later and say, 'Oh, my body is like this because I had three kids.'"
The former dancer said she put on a healthy 30 pounds during pregnancy by avoiding overeating and working out during her pregnancy.
Anderson's quick rebound only highlights the pressure many moms feel reading about Hollywood mothers or "momshells" (mother-as-bombshell) who seem to jump right back into their busy Hollywood careers looking svelte and stylish with no signs of baby weight.
More magazine editor-in-chief Lesley Jane Seymour told "GMA" last week that ordinary women need to remember that celebrities aren't just like us.
"Nobody can live to that standard," Seymour said. "[Celebrities] have $40,000 exercising gurus. You're not being paid for that. That is not your job. They have to get in shape in two weeks because they've got to go on the set. That is not the normal human being."
Before she became a trainer to the stars, Anderson struggled with her weight, especially after her first pregnancy with son Sam in 1988. The exercise guru said she packed on twice the amount of pounds she did with her daughter, giving in to cravings for milkshakes and hot dogs.
"I feel like I've lived an entire lifetime since then," said Anderson, who produced the Pregnancy Project, a series of nine exercise DVDs for pregnant women - while she was pregnant with Penelope.
But even Anderson admits it was hard to lose the weight after giving birth to her daughter.
"For 13 years I've been jumping around, dancing at such high levels all over the world and with no sleep for multiple hours a day. I thought, 'Please, I can bust out an hour of dance aerobics, no problem.' Wrong!" she said.
With 10 pounds to shed until she gets to her pre-pregnancy weight, Anderson said, "I know that the journey of getting back to your best level of performance physically is very hard, but it's an incredibly empowering place to be."