You can’t get through a supermarket check-out line without seeing the newest celebrity mom’s fab post-baby bod, as if the ability to shrink your uterus and shed excess fat is more miraculous than the human you produced from your body. And although some celebrities are super candid about their struggles — or at least their ambivalence — to dropping the baby weight immediately, many celebrities link breastfeeding and weight loss as the golden answer. From Beyoncé who claimed she “lost most of the weight from breastfeeding” to Mila Kunis, who told Jimmy Kimmel that “breastfeeding is like working out”. Even Kristin Cavallari told People that she owes all her postpartum weight loss to breastfeeding, saying that nursing is equivalent to running six miles a day.

Easy there, Cavalleri. Although there’s certainly a biological reason why breastfeeding might help a new mom lose weight, it’s also not as simple as a celebrity sound bite claims. Many new moms are under the impression that as long as they breastfeed, they can slip into their pre-pregnancy skinny jeans within the first week or so — I mean, isn’t it like running six miles a day? Turns out yes. . . and no.

“When you breastfeed, you use fat cells stored in your body during pregnancy — along with calories from your diet — to fuel your milk production and feed your baby,” Dr. Roger Harms, medical director of content for Mayo Clinic, wrote. “Weight loss during breastfeeding can occur even when you follow the recommendations to eat an additional 400 to 500 calories a day to keep up your energy.” That’s because the simple act of making breast milk can burn a whopping 300 to 500 calories a day.

I was actually in the lucky group that found it pretty easy to drop back to my pre-baby weight, but did my over-abundant milk supply have something to do with it? “It’s possible,” lactation consultant Mary Hickman says. “But every body is different, and many breastfeeding women, even those exclusively nursing, have trouble with the last 5 or 10 pounds. Weight loss can be rapid at first, and then taper off as nursing continues.” Hickman pinpoints pregnancy weight gain as the biggest indicator of how fast a new mom will drop the baby weight, rather than whether she breastfeeds or not.

Not every woman shares my experience, and not every woman has the same weight loss experience for subsequent pregnancies. After four years of nursing school and months working as a labor and delivery nurse, Chaunie Brusie followed the “breast is best” mantra and saw the weight fall off after her first baby. But looking back, she’s not so sure it was the breastfeeding. “I was shocked to discover that with my second and third babies, I struggled to lose any weight at all, despite regular exercise — until I was completely done breastfeeding,” Brusie wrote for Babble. “It felt like my body stubbornly clung to each and every last fat molecule in my cells as if they were all that stood between my baby and a miserable, slow death by starvation.”

Turns out that’s a pretty common experience. In fact, a study at the Cincinnati Children’s Hospital Medical Center found that non-breastfeeding women actually lost more body fat than lactating women in the six-month postpartum period, possibly because prolactin can act like an appetite stimulant in nursing moms, causing them to overeat. And, as Harms said, nursing moms do require more calories to keep up their milk supply. According to Kelly Bonyata of KellyMom.com, nursing moms should aim to eat at least 1,500 to 1,800 calories a day, possibly more. “The health of your baby and your milk supply has to come before weight loss,” Hickman says. “Most women aren’t going into breastfeeding because of the weight loss promises. It’s a demanding and rewarding process, regardless of what the scale says.”

So if you find yourself outside the Beyoncé camp, unable to drop your baby weight from breastfeeding alone, here are a few tips.